Umotrs of % Ulustum of Compnitibt ^oblocjn
AT HARVARD COLLEGE.
Vol. XXXIV. No. 3.
HAWAIIAN AND OTHER PACIFIC ECHINI.
THE ECHINOTHURID.E.
BY
ALEXANDER AGASSIZ and HUBERT LYMAN CLARK.
WITH THIRTY PLATES.
Plates 60-89.
[Published by Permission of George M. Bowers, U. S. Commissioner of Fish and Fisheries.]
CAMBRIDGE, U. S. A. :
^rintco for tljc ifluscum.
November, 1909.
CONTENTS.
No. 3. HAWAIIAN AND OTHER PACIFIC ECHINI. Based upon Collections made
by the U. S. Fish. Commission Steamer " Albatross " in 1902, Commander Chauncey
Thomas, IT. S. N., Commanding, and in 1906, Lieut. Commander L. M. Garrett,
U. S. N., Commanding. The Echinothurid^:. By Alexander Agassiz and
Hubert Lyman Clark. 72 pp. 30 plates. October, 1909.
CONTENTS.
Eckinothuridffl Wyv. Thom
Some Anatomical Features, Plates
60-63
The Spines, Pedieellarise, Sphse-
ridia, and Spicules, Plates 64-67 .
The Systematic Position of the
Echinothuridae
The Genera and Species of Echino-
thuridae ... •
Phormosoma Wyv. Thom. . . .
Phormosoma alternans de Meij.
Phormosoma verticillatum Mort.
Phormosoma rigidum A. Ag. .
Phormosoma adenicum Dod.
Phormosoma placenta Wyv.
Thom
Phormosoma Sigsbei A. Ag.
Phormosoma iudicum Dod. . .
♦Phormosoma bursarium
Ag., Plates 62, fig. 2
, Plates 62, fig.
fig. S
A.
63,
Echinosoma Pomel
Echinosoma hoplacantha A. Ag.
and CI
Echinosoma luculentum A. Ag.
and CI. •
Echinosoma hispidum Mort.,
Plates 62, fig. 3; 63, fig. 4 ;
67, figs. 4-11
Echinosoma tenue Pomel, Plate
67, figs. 12-21
Echinosoma Koehleri A. Ag.
and CI
Echinosoma zealandise A. Ag.
and CI
Echinosoma panamense Mort.,
Plate 67, figs. 1-8
Echinosoma uranus Pomel . .
Page
141
141
142
146
151
153
155
156
156
156
157
157
157
158
160
161
163
164
165
167
168
168
169
Paok
Echinosoma Pomel {continued).
Echinosoma Petersii A. Ag. and
CI 169
Kamptosoma Mort 169
Kamptosoma asterias Mort. . . 170
Kamptosoma indistinctum A. Ag. 170
Asthenosoma Grube 171
Asthenosoma varium Grube . . 172
Asthenosoma urens Saras. . . 172
Asthenosoma heteractis Bed-
ford 172
Asthenosoma Ijimai Yosh.,
Plates 62, fig. 1 ; 63, fig. 2. 173
Araeosoma Mort 174
Araeosoma thetidis A. Ag. and
CI., Plates 66, figs. 6-17; 68-
70 176
Araeosoma bicolor A. Ag. and
CI., Plates 64, figs. 1-8; 71 ; 72 179
Araeosoma pellucidum A. Ag.
and CI 181
Araeosoma eurypatum A. Ag. and
CI., Plates 66, figs. 1S-19; 73-
75 181
Araeosoma leptaleum A. Ag. and
CI., Plates 76 and 77 ... . 183
Araeosoma hystrix A. Ag. and
CI. ... '. 186
Arasosoma pyrochloa A. Ag. and
CI., Plates 66, figs. 1-4 ; 78-
80 186
Araeosoma Belli Mort., Plate 66,
fig. 5 188
Araeosoma violaceum Mort. . . 190
Araeosoma coriaceum Mort. . . 190
Araaosonia tessellatum Mort. . 190
Araeosoma fenestratum Mort.,
Plate 66, fig. 20 190
* Hawaiian species.
140
HAWAIIAN AND OTHER PACIFIC ECHINI.
Page
Araeosoma Mort. (continued).
Aroeosoma gracile A. Ag. and CI.,
Plates 81, figs. 3, 4 ! 82, figs.
5-8 191
ArteosomaOwstoni Mort., Plates
81, figs. 1, 2, 5, 6 ; 82, figs.
1-4 192
Sperosoma Kcehler 194
Sperosoina Grimaldii Koehler . 196
Sperosoma quiucunciale de
Meij 196
Page
Spierosoma Koshler (continued).
Sperosoma giganteum A. Ag.
and CI., Plates 64, figs. 9-12;
65, figs. 1-3 ; 83-86 .... 197
*Sperosoma obscurum A. Ag.
and CI., Plates 62, fig. 4; 63,
fig. 1 ; 65, figs. 4-14 ; 87-89 199
Sperosoma biseriatura Dod.,
Plate 65, figs. 15-20 202
Sperosoma durum Dod 203
Plates and Explanation of Plates . . 204
* Hawaiian species.
HAWAIIAN AND OTHER PACIFIC ECHINI.
Collected by the U. S. Fish Commission Steamer "Albatross," Commander
Chauncey Thomas, U. S. N., Commanding in 1902, and Lieut. Com-
mander L. M. Garrett, U. S. N., Commanding in 1906.
ECHINOTHURIDiE Wyv. Thorn.
Some Anatomical Features.
Plates 60-63.
ALTnouGn various writers1 have discussed the anatomy of the Echino-
thuridoB in more or less detail, and some have published figures to illustrate
certain anatomical peculiarities, it has seemed to be desirable to give a few-
figures showing the general arrangement of the alimentary canal and the
lantern in some of the species, whose anatomy has not hitherto been figured.
As our investigations have led us to believe that the Echinothuridas and
Diadematidae are nearly related families, we have also added a few figures
showing the anatomy of several species of Diadematidas.
A comparison of the figures given on Plates 62 and 63 shows that the
genera of Echinothuridae differ not a little among themselves in the details
of their structure. It is, nevertheless, instructive to compare these figures
with those of the genera of Diadematidae given on Plates 60 and 61. The
oesophagus, for example, is shortest in Echinothrix (PL 60, fig. 3), some-
what longer in Micropyga (PL 61, fig. i) and Phormosoma (PL 62, fig. 2),
much longer in Echinosoma and Sperosoma (PL 62, figs. 3, 4), and longest
in Asthenosoma (PI. 62, fig. 1) and Astropyga (PL 61, fig. 3).
The alimentary canal of Phormosoma is remarkably different from
that of Asthenosoma (compare figs. 1 and 2, PI. 62), but it is interesting
to note that that of Echinosoma (PL 62, fig. 3) is quite intermediate.
1 Wyville Thomson, 1S74: "Porcupine" Echinoidea, Trans. Roy. Soc. London, 164, pt. 2, Pis.
LXIII-LXVII. A. Agassiz, 1881 : " Challenger " Echinoidea, Pis. XII, XIV, XVIII". Paul and
Fritz Sarasin, 1888: Ergeb. Nat. Forsch. Ceylon, I, Pis. XII-XVII. Kciehler, 189S : "Hirondelle"
Echinides, Pis. IV and IX. Schurig, 1906 : Wiss. Ergeb. d. Deutsch. Tiefsee-Exp. 5, lfg. 3,
Pis. LI-LIV.
142 HAWAIIAN AND OTHER PACIFIC ECHINI.
That of Sperosoma (PI. 62, fig. 4) shows some noticeable resemblances to
the arrangement in Echinothrix (PI. 60, fig. 3), though it has certain
peculiarities of its own, in addition to the long, slender oesophagus.
There can be no question that the general arrangement of the canal in
Asthenosoma (PI. 62, fig. 1) is quite as near what we find in Astropyga
(PI. 61, fig. 3) as it is to that of any genus of Echinothurids.
A comparison of the lanterns and perignathic girdles figured on Plate 63
with those of the three genera of Diadematidoe (PI. 60, fig. 4 ; PI. 61, figs. 2,
4) reveals two very important differences. In the Echinothurids, the apo-
physes, whether conspicuous as in Phormosoma (PI. 63, fig. 3), or relatively
inconspicuous as in Asthenosoma (PI. 63, fig. 2), are single, in keeping with
the presence of the single primordial interambulacral plate, while in the
Diudematids they are paired. In the Echinothurids (PL 63), the Stewart's
organs, though very different in appearance from those of the Cidaridaa, are
well developed,1 while in the Diadematids they are either wholly wanting
or are reduced to mere rudiments as shown in Echinothrix (PI. 60, fig. 4).
Aside from these two points, the differences between the girdle and lan-
tern of Phormosoma and those of Asthenosoma are as great as those
which distinguish Phormosoma from Astropyga, or Echinothrix from Micro-
pyga. We find there is noticeable individual diversity in certain points,
such as the bulk of the auricles and the amount of forking at the end of
the compasses, so that these features are of little value in determining
generic limits.
The Spines, Pedicellari^:, Sph2eridia, and Spicules.
Plates 64-67.
The spines of the Echinothuridte show so much diversity of form, aside
from the differences between primary, secondary, and miliary spines, that
they deserve a special paragraph. They may be conveniently classified
under four heads, — naked spines, sheathed spines, glandular spines, and
hoofed spines. The naked sjmies are the ordinary spines, more or less
abundant on all parts of the test; they may be slender or stout, pri-
maries, secondaries, or miliaries ; they may be either sharp or blunt, or
rarely, widened and flattened at tip, long or short, smooth or rough ; they
1 Those writers who have said that Stewart's organs are rudimentary or wanting in certain
Echinothurids have either had poor material or have overlooked these long, slender outgrowths.
Or else there is more individual diversity than would naturally be expected.
ECHINOTHURIDiE. 143
are rarely verticillate as in Diadema. They are commonly hollow, though
some of the very slender ones and those on the buccal membrane are oft en
solid, at least in their distal half. The sheathed spines are commonly
primary spines, but may be secondaries or even miliaries; when the
sheath of skin is thick and loose they are conspicuous and unmistakable,
but when the sheath is thin and close-fitting they can scarcely be dis-
tinguished from ordinary "naked" spines, which are, of course, really
covered by the skin. Sheathed spines may be either actinal or abactinal
in position, and the sheath may be either cylindrical or distally swollen ;
when cylindrical, it may have one or more circular constrictions. The
glandular spines are secondaries or miliaries, exceedingly sharp, and pro-
vided with a poison-gland at the tip. They are commonly abactinal in
position, and may be arranged in regular series on the interambulacra. The
hoofed spines are always actinal primaries, and are the most conspicuous
spines on the test when present. They are usually hollow, even the shining
white hoof-shaped swelling in which they terminate being only loosely
filled with calcareous strands ; but in some species the hoof and the distal
half of the spine are perfectly solid ; there is more or less diversity how-
ever in different spines, even of a single individual. Unfortunately the
hoofs are very easily broken off, and otherwise good specimens may show
few or none. All four of these different kinds of spines may occur on
a single individual, but as Mortensen has pointed out, species which have
sheathed spines actinally do not have hoofed spines.
The pedicellarice of the Echinothuridas have been so fully discussed and
satisfactorily figured by Mortensen and Doderlein, it is hardly necessary
to devote much space to their description. There are four different sorts,
two or more of which may be found in any individual. The triphyllous
pedicellaria? (PI. C4, fig. 3) are always present, and always have three valves,
which are broadest at or near the tip and are well separated from each
other just below the middle when the pedicellaria is closed ; the valves
(PI. 64, figs. S, 12) are provided with a " cover-plate " which is usually more
or less perforated. These pedicellaritB are abundant on almost all parts of
the test, and are borne on long slender stalks, which are several times as
long as the head. The tridentate pedicellaria? (Pis. 64, fig. 9 ; 66, figs. 1, 2,
15, 17; 67, figs. 2, 3, 4, 6, S, 9, 12, 17) are nearly or quite as common as the
triphyllous, but are very much more diverse in size and form. They occur
on all parts of the test, but their abundance varies greatly in different indi-
144 HAWAIIAN AND OTHER PACIFIC ECHINI.
viduals. The length of stalk is also very variable, though it commonly
exceeds that of the head. The structure of the stalk is of the usual type
in the Diadematidte, a cylinder of irregularly but closely united coarse rods.
It is very interesting to note that in Kamptosoma the stalk is made up
of "long threads, almost only united at the ends" (Mortensen); the stalk
in this genus, therefore, bears the same relation to the stalk in other Echino-
thurids that the stalk of the pedicellarioe in Micropyga does to that of the
other Diadematids, — a very notable case of " parallelism." The valves of
the tridentate pedicellarioe vary so much in size and form that a general de-
scription of them is impracticable, but certain kinds are very constant and
easily recognizable, and these deserve a few words. First of all are involute
valves, which are more or less curved and meet only at tip (PI. 66, fig. 1) ;
in these the margins of the blade are rolled in, forming a nearly cylindri-
cal middle part of greater or less length between the base of the blade and
the somewhat expanded tip ; secondly, there are contiguous valves, which
are straight and in contact for nearly their entire length, — these may be
very broad (PI. 65, fig. 18), or rather narrow (PI. 64, fig. 5) ; a third sort
may be referred to as convergent valves, which are straight or little curved,
little or not at all involute, meeting only at tip or for their distal half ; such
valves are shown on PI. 65, fig. 5 ; see also PL 67, figs, b, 12. Although
these three sorts of valves are usually recognizable with ease, they do inter-
grade more or less (PI. 65, fig. 4; 66, fig. 2). The ophicephalous pedicellaria}
(PI. 65, figs. 1, 2) are much less common, as a rule, than the tridentate,
and have been found as yet in only a comparatively few species ; they are
strongly constricted at the middle, and the articular loops on the valves
(PI. 65, fig. 3 ; 67, fig. 21) are well developed ; these pedicellaria? show no
tendency to intergrade with the other forms. The fourth form of pedicellaria
was first described by Wyville Thomson as a " tetradactyle " pedicellaria,
and Mortensen has retained the name. Unfortunately, however, the num-
ber of valves is often three or five, so that the " tetra" — is very inappro-
priate ; we would suggest that this form be called simply the dactylous
pedicellarise. They are known only from certain species of Araaosoma,
and show considerable diversity in the form of the valves ; these may be
long and slender, united only near the base and quite free distally (PI. 66,
fig. 20), or they may be much shorter and well surrounded by tissue as
de Meijere figures them, or the valves may be wholly imbedded in tissue
(PL 64, fig. 1). The valves differ notably in shape (compare PL 64, fig. 4, and
ECHINOTHURIDA. 1 | .",
66, fig. 20) and may even be greatly reduced, with the expanded tip entirely
lacking; this form, which occurs in A.- pellucidum, was at first regarded by
Mortensen as a " globiferous" pedicellaria; but he was subsequently satisfied
by de Meijere's evidence, that it is simply a degradational form of dacty-
lous pedicellaria. There are no globiferous pedicellaria? known in the
Echinothurida?.
As Doderlein has well pointed out, the three families Aspidodiadematida?,
Diadematida?, and Echinothurida? show such agreement in the essential
features of their pedicellaria? that they form a group apart from the other
regular Echini, and arouse the suspicion that they are mutually interrelated.
In the absence of globiferous pedicellaria? (present only in Centrostephanus)
they agree with the Salenida? and Arbaciada?, and differ markedly from the
Cidarida?, Echinometrida?, and Echinida?. Their mutual agreement in triden-
tate pedicellarise is obvious, but in view of the great diversity of form which
these pedicellaria? show in the three families, and of the fact that very
similar pedicellaria? occur in other families, no great weight can be laid on
this point. The ophicephalous pedicellaria? of the Echinothurida? are pe-
culiar but are as much like those of the Diadematida? as of any other echini,
excepting only some of the spatangoids. The triphyllous are similar to those
of the Aspidodiadematida? ; they are less like those of Astropyga and Micro-
pyga, but still the resemblance even here is not to be ignored.
The sphceridia of the Echinothurida? (Pis. 66, figs. 4, 5, 18 ; 67, fig. ll), as
in the Aspidodiadematida? and many Diadematida?, are more or less numerous
in each ambulacrum and occur at the inner lower side of the tube-feet in the
innermost series. In Phormosoma they are also present next to the feet of
the middle series. They may be confined to the actinal surface of the test,
but commonly they extend above the ambitus. They sometimes accompany
the tube-feet nearly or quite to the ocular plate, and occasionally they may
be found on the buccal plates. In Phormosoma they are nearly spherical,
but in the other genera they are more or less elongated ; sometimes the
length and appearance (PI. 66, fig. 18) indicate clearly their origin as modi-
fied spines.
The calcareous spicules of the tube-feet are commonly in the form of perfo-
rated plates (PL 65, figs. H, 20), which show great diversity in form and
size. In some species, however, the spicules, either in the basal part of the
foot or throughout its length, are simply more or less irregular triradiate
rods (PI. 66, fig. 13), similar to those found in the Diadematida?. There
10
146 HAWAIIAN AND OTHER PACIFIC ECHINI.
seems no reason to question the fundamental triradiate origin of even the
larger perforated plates, so that we have here again a suggestion of Diadematid
relationship.
The Systematic Position of the Echinothurid^e.
In all discussion as to the proper position of the EchinothuridEe in our
classification of the Echini, the crucial point is as to the stress that shall be
laid on the occurrence of regular series of ambulacral plates on the actino-
stome. If this character is regarded as of fundamental importance, then of
course the Echinothurids stand quite apart from all the other regular Echini,
excepting only the Cidaridce ; but if the possibility be admitted that this
character has appeared independently in the Echinothurids, or has been
retained by them, while lost by the other families, then we may well examine
with care the other characters of the family to see if we cannot ascertain its
relationships.
Mortensen is one of those who hold to the fundamental importance of
the Echinothurid actinostome, and has expressed himself (1904) as favoring
their union with the Lepidocentridce in a suborder (Streptosomata) apart
from the other Ectobranchiate Regulares. Doderlein, on the other hand, has
expressed himself ' (1906) as believing in the close relationship of the Echino-
thurids and Diadematids, and he recognizes a suborder (Diadematida) which
includes the Streptosomata as a special " tribe" containing the Echinothurids
only and the Stereosomata, a tribe made up of the Diadematidse and its
closest allies. In attempting to reach a correct conclusion on the question, it
has seemed to us that it would be helpful to tabulate in parallel columns all
the morphological characters of the Echinothuridoe and Diadematidse. By so
doing the similarities and differences will be made to stand out more vividly,
and we may perhaps be able to decide whether the resemblances indicate
relationship or not. The characters are arranged in what seems to us to be
the order of importance.
The careful comparison of the ambulacra in Echinothrix, Astropyga,
Micropyga, Phormosoma, Asthenosoma, and Sperosoma demonstrates that
the differences are superficial, and that in all these genera each ambulac-
ral plate consists of three elements, of which the middle one (primary)
is largest, while the adoral and aboral (secondary) elements show great
diversity in size and position. In Echinothrix the secondary elements are
rather large and lie next to the interambulacrum ; the pore-pair of the
ECIIIXOTIIUIMD.K.
147
TABLE OF THE MORPHOLOGICAL CHARACTERS OF THE ECHINOTIIUR1H i:
AND DIADEMATHXE.
Structure of
Ambulacra.
Interambulackal
Areas.
Primary Tubercles.
Abactinal System.
ACTINOSTOME.
Teeth.
Jaws.
Perignathic
Girdle.
Arrangement of
Tube-feet.
Spines.
Stewart's Organs.
Gills.
Alimentary Canal.
Pedicellari.e.
Globiferous.
Ophicephalous.
Triphyllous
Tridentate.
Tube-feet.
Spileridia.
Calcareous
Spicules.
Color.
Size.
Diadematid.e.
Diadematoid ; each compound plate
consists of a middle primary, and
abactinal and actinal .secondary ele-
ments. Adoral imbrication usually
slight or wanting.
Interambulacral plates bevelled on
edge.
Primordial interambulacral plate re-
sorbed. Aboral imbrication not
usually noticeable. Without evi-
dent membranous interspaces.
Perforated ; usually crenulated.
Large; anal system covered by nu-
merous small plates ; anal tube often
present; commonly 2-5 oculars in
contact with anal system; genito-
ocular ring continuous, with rare ex-
ceptions ; genital plates seldom split.
With five pairs of buccal plates and
more or less numerous small scat-
tered plates, either confined to, or
much more conspicuous in the am-
bulacral areas.
Grooved.
More or less erect, with open foramen
magnum.
Continuous; auricles and apophyses
more or less extensively developed.
In three longitudinal series, com
monly; sometimes in two; rarely
in one actinally.
Hollow; long, usually verticillate,
sometimes smooth; hoofs and con
spicuous skin-sheaths wanting.
Rudimentary or usually wanting.
Well-developed.
Long and large; oesophagus long and
more or less coiled.
Wanting (except Centrostephanus).
Valves constricted at middle; blade
deeply hollowed, with little calca-
reous material within.
Flat and leaf-shaped, commonly with-
out cover-plate.
Very diverse, both large and small.
With sucking disc actinally, but usually
not abactinally.
Usually numerous, not sunken in pits,
arranged in a vertical series, at inner
side of inner series of tube-feet, in
each half ambulacrum.
Essentially triradiate, often forming
perforated plates.
Usually very dark, black, olive, purple
or red ; sometimes light ; spines often
banded.
Usually large, up to 150 mm. h. d.
Eciiinothukid.e.
Essentially diadematoid; some di-
versity shown in relative size and
position of plate-elements. Adoral
imbrication usually well-marked.
Interambulacral plates imbricating.
Primordial interambulacral plate re-
tained. Aboral imbrication more or
less marked. Membranous inter-
spaces often very marked.
Perforated; non-crenulated.
Large; anal system covered by nu-
merous small plates; anal tube
wanting; all oculars in contact with
anal system ; genito-ocular ring
often discontinuous; genital plates
often split.
Covered by five double columns of
perforated ambulacral plates.
Grooved.
More or less inclined, with open fora-
men magnum.
Continuous; auricles and apophyses
more or less extensively developed.
In one, two, or three longitudinal
series.
Hollow; short, usually smooth and
very rarely verticillate; hoofs or
conspicuous skin-sheaths often pres-
ent, at least on actinal primaries.
Well-developed ; rarely rudimentary,
and possibly wanting in some in-
dividuals.
Commonly well-developed.
Long and large; oesophagus long and
more or less coiled.
Wanting.
Valves very wide near tip and deeply
constricted, essentially as in Dia-
dematida?.
Flattened and widened at tip, with
cover-plate.
Very diverse, both large and small.
No sucking disc abactinally, and often
not actinally.
As in Diadematidse.
Usually perforated plates, often show-
ing triradiate origin; sometimes tri-
radiate spicules.
Deep purple, red, dull yellowish, gray,
or greenish; spines often banded.
Large, 70-320 mm. h. d.
148 HAWAIIAN AND OTHER PACIFIC ECHINI.
primary element is the outermost of the three, that of the adoral sec-
ondary is innermost, while that of the aboral secondary is intermediate ;
we thus get the characteristic arrangement of the pore-pairs in arcs of
three. In Astropyga, only the alternate primary elements are like each
other in form, one series being broadest at the inner end, and those
alternating with them broadest at the middle ; the secondary elements
accompanying the latter occupy the same position they do in Echino-
thrix, while those which accompany the plates with a wide inner end
lie close to that end ; the pore-pairs of the primary elements are here
median in position, while the pore-pairs of the secondary elements alter-
nate, two pairs being inner, then two outer, then two inner, etc. The
characteristic arcs of three are thus maintained. In Micropyga the ele-
ments are arranged essentially as in Echinothrix, but the pore-pairs of
the primaries alternate in position, as well as those of the secondaries
(as in Astropyga) ; thus, if the pore-pair of a given primary element lies
at the outer end of the plate, the pore-pairs of the secondary elements of
the same plate occupy a median position, while in the adjoining plates
the pore-pairs of the primary elements will be median in position and
those of the secondary elements take an outside position ; we thus get
the double column of pore-pairs characteristic of Micropyga. In most of
the Echinothuridae the condition is essentially as in Echinothrix, but the
secondary plate elements remain so small and are so generally pushed out
of position, the appearance of an ambulacrum is quite different from that
of any Diadematid ; the abactinal arrangement of the pore-pairs is com-
monly as in Echinothrix. In Sperosoma, the secondary plate elements
become so large actinally, they separate the inner half of the primary ele-
ment from the outer, and there thus appear to be four columns of plates
in each half-ambulacrum. Mortensen says, in his diagnosis of Sperosoma,
" The secondary ambulacral plates on the actinal side of the same size as
the primary ones." We do not find this to be the case in the type-
species, Grimaldii, nor in any other of the species we have examined ; it
seems to us that the halves of the primary element are, with rare excep-
tions, noticeably larger than the secondary elements.
The difference between the Echinothuridae and Diadematidoa in the
imbrication of the coronal plates is one of degree and not of kind, and
the same is true of the presence of membranous interspaces between the
plates. The difference between the test of an Echinothrix or Centroste-
KtinxoTiniMD.i:. 149
phanus and that of an Astropyga or Micropyga is fully as great in these
particulars as that between Astropyga and such Echinothurids as Arae-
osoma Owstoni or A. thetidis. In fact the resemblances between the two
families in the general character of the test are far more weighty than
are the differences. The crenulation of the primary tubercles is gener-
ally marked in the Diadematidae, but it is quite wanting in Micropyga
and Lissodiadema, in which genera the tubercles are like those of the
Echinothurids.
The abactinal system of the Echinothurids represents merely an
extreme condition of the Diadematid form. There is really no difference
of importance between the arrangement of the plates in some species of
Anvosoma and that which we find in Astropyga and Chcetodiadema.
When the abactinal system of Leptodiadema is compared with that of
some species of Echinosoma the differences are most striking, but when
we examine other genera we can trace every step of the transition from
one into the other.
As regards the actinostome, it must be admitted that the fully plated
buccal membrane of the Echinothurids is quite unlike anything to be
found in the Diadematidae. As Dciderlein has well pointed out, we may
regard the plating as a character developed in the Echinothurida? inde-
pendently, an interesting parallelism with what is found in the Cidaridas
and some Palaeozoic Echini, or we may look on it as a heritage, from
some ancestral form, which the Diadematidie have lost. The actinosto-
mal plates of the Diadematidae, aside from the customary buccal ten, are
usually numerous and often abundant. And it is interesting, if not impor-
tant, to note that in nearly all Diadematids these plates are confined to,
or at least are much more abundant in, the ambulacra, and sometimes
form a double column in each ambulacrum. In Astropyga it is these
ambulacral plates which carry the pedicellarice, and in young specimens
what appear to be rudimentary tube-feet are sometimes present ; we have
never found any visible perforation of the plates, however. We incline to
the view, nevertheless, that the condition of the actinostome in the Dia-
dematids indicates the gradual loss of ambulacral plates similar to those
of the Echinothurids.
The teeth, jaws, and perignathic girdle in the two families are so simi-
lar, we have not found any important constant difference. The jaws are
decidedly more inclined in the Echinothurids than in Diadema, but Astro-
150 HAWAIIAN AND OTHER PACIFIC ECHINI.
pyga and Micropyga are intermediate in this respect. The lantern of
Astropyga is surprisingly like that of Asthenosoma Jjimai. There is great
individual diversity in both families in the amount of calcification in the
perignathic girdle. In some specimens the auricles are very moderate and
the apophyses almost wanting, while in others the auricles are enormous
and the apophyses stout.
In the internal anatomy the two families are much alike, except that
the Echinothuridoe have well-developed Stewart's organs and longitudinal
body-wall muscles, both of which are rudimentary or wanting in the Dia-
dematidte. The Stewart's organs are undoubtedly a heritage, and their
form would seem to indicate that they now have little functional impor-
tance. The body-wall muscles have doubtless been developed in connec-
tion'with the increasing mobility of the test. The gills of the two fami-
lies and the sphajridia show the greatest similarity.
The spines are fundamentally alike in their structure, commonly hol-
low, though not infrequently more or less solid, at least near tip. They
are much longer in many Diadematidaa than in the Echinothuridaa, but
Astropyga and Micropyga are more like the latter family. The presence
of poison-tipped spines is a character found in both families, but hoofs
and skin-bags seem to belong to the Echinothuridoa exclusively. It should
be noted, however, that Dtiderlein has figured spines in Dermatodiadema,
which are so formed as to almost warrant their being called " hoofed,"
and somewhat similar spines occur in Micropyga. Some of the spines of
Echinothrix, moreover, might almost be called " sheathed." Such special
modifications of the spines cannot be regarded as of great weight in esti-
mating relationships.
The similarities between the two families in their pedicellariaa have been
referred to above ; they have also been discussed quite fully by Dbderlein.
The fundamental resemblance of the spicules in the tube-feet is noteworthy,
though they are much more fully developed in most Echinothuridce than
in the Diadematids. In color and size the similarity between the two fam-
ilies is more noticeable than the difference. The banding of the primaries,
so marked in young Diademas, is noticeable in some Asthenosomas. The
Diadematidse and the shallow-water Ecliinothurids are tropical and partic-
ularly East Indian forms. The deep-water Ecliinothurids have spread both
nqrth and south of the tropics.
In view of all these facts, we find ourselves driven to the opinion that
ECIIINOTIIURID^E. 151
the relationship between the Echinothuridoe and Diadematidtc is very close.
We cannot believe that the many points of resemblance are either coinci-
dences or examples of parallelism. On the other hand, it seems clear that
many of the differences, such as those in the abactinal system and test, are
due to the increased size of the Echinothurids accompanied by decrease in
calcification. The relationship between Astropyga and Micropyga on the
one hand and Araeosoma on the other is very close ; were it not for the
difference in the actinostome they would certainly be regarded as belonging
in a single family. The recognition of a separate suborder (Streptoso-
mata) for the Echinothuridse, based on the flexibility of the test, seems to
us quite unnecessary. The test of several Echinothurids is little or no
more flexible than that of Astropyga and Micropyga, and it is certainly an
exaggeration of the differences between these genera and the Echinothu-
ridaa to place them in different suborders. The Aspidodiadematidse, Dia-
dematidas, and Echinothuridae form a natural group with some interesting
primitive characters, and if suborders of the Diadematoida are to be recog-
nized they should certainly form one together.
The Geneea and Species of Echinothurids.
The Echinothuridae are a fairly homogeneous and well-defined group, the
limits of which are so clear that there has never been any question raised
as to whether a given recent species were an Echinothurid or not. Eor many
years, only two genera (Phormosoma, Asthenosoma) were recognized, but
in 1897 Koehler described a new form (Sperosoma), the actinal ambulacra
of which are quite unique. In 1903 Mortensen split the family into ten
genera, and suggested the possibility of two more ; while he gave attention
to the structure of the test, his classification was based chiefly on the
characters furnished by the spines and pedicellariae, especial emphasis
being placed on the latter. Three of his genera (Calveria, Hapalosoma,
Tromikosoma) are based almost exclusively on the pedicellariae, and he
has suggested in later writings that they might not be maintained, a sug-
gestion in which we fully concur. Mortensen says "it is the spines, the
pedicellariae, the tube-feet, and the spicules which bear the principal part
in the new classification of the Echinothurids." " Of course also the struc-
ture of the test is always of importance, but the all predominant importance
that has hitherto been attached to the form and mutual relation of the
plates will have to be very much reduced." — "The arrangement of the
152 HAWAIIAN AND OTHER PACIFIC ECHINI.
plates is generally only to be seen in dried specimens. But the Echinothu-
rids are only very little adapted for preservation in dried state, and if the
material in hand be slight, one does not like to destroy it for the sake of
determination." — "The sphaeridiaB . . . show no differences so great that
they can be of any systematic importance. The pedicellarite, on the other
hand, are of the greatest importance with regard to the classification." It
is because we do not think that the " spines, the pedicellarige, the tube-feet,
and the spicules " should " bear the principal part " in a satisfactory class-
ification of the Echinothurids, and because we consider " the structure of the
test," using that phrase in the widest sense, to be of " all predominant
importance" that we are obliged to dissent from Mortensen's classification.
Moreover, we find the Echinothurids admirably adapted "for preservation
in dried state " ; all of the photographic plates given herewith and those
in the report on the Panamic deep-sea Echini (Mem. M. C. Z., XXXI) are
from dried specimens ; so far from drying, destroying the specimens, it pre-
pares them very satisfactorily for systematic study. As will be noted in our
discussion of the genus Phormosoma, we find the sphteridia afford an in-
teresting character of real " systematic importance."
Our studies of the Echinothuridse have led us to the conclusion that
there are six natural genera in the family. We believe Mortensen is right
in limiting Phormosoma to the group of species allied to placenta, but we
fail to find any character of importance by which his genera Hygrosoma
and Tromikosoma are to be distinguished from Echinosoma Pomel. Of
course, if one considers the possession of certain peculiar pedicellariae, in
small numbers, by some individuals, as a valid generic character, then one
must accept Mortensen's groups, but, as we have often stated, we cannot
believe such a criterion is right. The peculiar ambulacra of Kamptosoma
and Sperosoma warrant the recognition of those genera, while the numer-
ous, small, uniform primary tubercles, bearing sheathed spines, which
cover the abactinal surface of Asthenosoma, make that genus, as limited
by Mortensen, an easily recognized group. We have not been able to
find any satisfactory characters by which Mortensen's genera Hapalosoma
and " Calveria " are to be distinguished from Arseosoma, and we have
therefore united the three groups under the last name.
The six genera which are thus accepted by us may be distinguished
from each other as follows :
PHORMOSOMA. 153
Actinal tube-feet in a single (or rarely two) more or less irregular series.
Primary ambulacral plates throughout most of ambulacra accompanied,
each by two secondary poriferous elements.
Many actinal primary spines enclosed in skin-bags, none with
hoofs; abactinal and actinal surfaces strikingly and abruptly
unlike Phormosoma.
Actinal primary spines not enclosed in skin-bags, some at least
ending in hoofs; abactinal and actinal surfaces not strikingly
and abruptly unlike Echinosovia.
Primary ambulacral plates, each accompanied by a single secondary
element or none Kamptosoma.
Actinal tube-feet in three more or less distinct series.
Each half of an ambulacrum, actinally, consists of a column of wide
low primary plates, each accompanied by two small secondaries.
Abactinal surface covered by numerous small primary tubercles
none of which are conspicuously larger than the others ; abac-
tinal primary spines encased in loose skin-sheaths Asthenosoma.
Abactinal surface with at least 30 conspicuous primary tubercles ;
abactinal primary spines not encased in loose skin-sheaths . . . Arceosoma.
Each half of an ambulacrum, actinally, consists of four columns of
plates, the two median columns made up of the secondary plate-
elements, the inner column made up of the inner halves of the pri-
mary plates, the outer column, of the outer halves Sperosoma.
Phormosoma.
Wyville Thomson, 1872. Proc. Roy. Soc. Edinburgh, VII, 84, p. 617.
Type-species, Phormosoma placenta Wyville Thomson, 1. c.
It seems to us desirable to accept Mortensen's limitation of this genus,
as the group is well defined and easily recognized. The test is rather rigid,
with actinal side markedly different from abactinal. The actinal primary
tubercles and areolae are large, while the. loose skin-sheaths' of the spines
are very characteristic. We beg to call attention to the arrangement of the
nearly spherical sphteridia, an interesting generic character overlooked by
Mortensen but which seems to be very constant. They are present actin-
ally on both secondary elements of each primary plate. Of course one
occasionally finds a secondary plate-element actinally which has no sphae-
ridium, but it is usually clear that the absence is accidental. In all other
Echinothurids, only the inner (lower) secondary element carries a sphae-
ridium. This genus, as now limited, contains eight recognizable species, but
they are closely related to each other and the lines of separation are not
distinct. Both Mortensen (1903) and Doderlein (1906) are inclined to
regard rigidum A. Ag. as a synonym of placenta, in spite of its great geo-
154 HAWAIIAN AND OTHER PACIFIC ECHINI.
graphical separation from that species. The size and arrangement of the
abactinal pores are so different from what is found in specimens of placenta
of the same size as the type of rigidum, that we think it better to keep the
latter separate, at least until moi'e material is available. Doderlein con-
siders a form of placenta which he calls Sigsbei recognizably distinct from
placenta proper, because of fewer and higher abactinal coronal plates.
Mortensen (1907) finds that this difference is not constant, but believing
the tridentate pedicellaria? of true placenta to differ from those of " Sigs-
bei" he thinks the latter may be a recognizable variety. Examination
of a considerable series of specimens of both P. placenta and P. bursa-
rium has satisfied us that in those two species, the height, and conse-
quently the number, of coronal plates is subject to considerable individual
diversity not associated with definite localities, and that the tridentate
pedicellarioe are also very variable. Specimens from the same or adjoining
stations have very different pedicellarias; the best illustration of this is
found in two specimens of bursarium from Stations 5082 and 50S4 ; the
specimen from 5082 has only short and thick tridentate pedicellariaB, while
in the one from 5084 these pedicellaria; are longer and more slender than
in any Phormosoma we have seen. It may be well to add that other speci-
mens are intermediate between these two extremes. In view of these facts,
we do not think that the form to which Doderlein and Mortensen refer can
well be distinguished, but we are now satisfied that P. Sigsbei is really as
valid a species as most of those in the genus, if we recognize others than
placenta. The name was originally applied to the Phormosoma collected by
the " Blake " west of the Lesser Antilles. Subsequently this form was con-
sidered identical with the Phormosoma collected off the eastern coast of the
United States, and all were determined as P. placenta. Recent examination
of the Caribbean specimens, and comparison with large numbers of Phormo-
soma from both the Atlantic and Pacific Oceans, have led us to believe that
they are distinct from placenta and somewhat nearer bursarium. We have
decided therefore to revive the name Sigsbei for them ; if the American
form of placenta, usually having short, thick pedicellariaa and relatively few
coronal plates is to be distinguished from the European form, a new name
must be given to it. In this connection it may be well to state that a
renewed examination of the specimens of young Phormosomas, the figures
of which ("Blake" Echini, PI. XV) are criticised by Mortensen ("Ingolf"
Ech., Pt. I, p. 69), has satisfied us that those figures are essentially correct.
PH011M0S0MA ALTERNANS. 155
Mortensen dismisses the possibility of the differences between his specimens
and these figures being specific, by saying he has had specimens from the
Gulf of Mexico which are exactly like those from Davis Strait, where his
young specimens were taken. This is interesting as confirming our opinion
that the Lesser Antillean species is distinct, and also as showing that
placenta extends its range as far southwestward as the Gulf of Mexico.
The eight species of Phormosoma which we here recognize may be dis-
tinguished from each other as follows :
'S"
Primary tubercles of ambulacra, abactinally, very much smaller than
those of interambulacra and arranged in four vertical series .... altemans.
Primary tubercles of ambulacra, abactinally, not conspicuously smaller
than those of interambulacra.
Abactinal primary spines rough with minute teeth which are in
whorls on distal part of spine verticillatum.
Abactinal primary spines smooth, or at least never verticillate.
Abactinal primary tubercles small and rather numerous (300-
500), occurring on all or nearly all the coronal plates.
Ambulacral pores large, in a nearly vertical series at
extreme outer end of ambulacral plates, abactinally . . rigidum.
Ambulacral pores smaller, in more oblique arcs of three
abactinally, and not at extreme outer end of plates.
Actinostome small (less than .30 h. d.), little larger
than abactinal system adenicum.
Actinostome more than .30 h. d., distinctly larger
than abactinal system placenta.
Abactinal primary tubercles larger and less numerous (70-
300), wanting on many of the upper coronal plates.
Abactinal arcs of pores few and nearly vertical, rarely
exceeding ten even when there are nine interambulacral
plates Sigsbei.
Abactinal arcs of pores 12-25, quite oblique.
Abactinal primary tubercles few (70-150), large, con-
fined to peripheral half of test indicum.
Abactinal primary tubercles more numerous (150-
300), smaller, not confined to peripheral half of
test hursarium.
Phormosoma alternans de Meij.
Phormosoma alternans de Meijere, 1903. Tijdschr. Ned. Dierk. Ver., (2) VIIT, p. 2.
1904. Ech. " Siboga " Exp., Pis. Ill, figs. 21, 22 ; XII, figs. 148-14$.
Dutch East Indies ; 386 fathoms.
Although this species is known from only a single specimen (very dark
brown, 52 mm. in diameter), it seems to be better characterized than any of
the other species recognized as distinct from placenta. Its general facies,
both with and without the spines, would seem to be quite different from that
156 HAWAIIAN AND OTHER PACIFIC ECHINI.
of any other species, but further material is necessary to determine how
constant these characters are and what are the limits of their variation.
Phormosoma verticillatum Mortens.
Phormosoma verticillatum Mortensen, 1904. Ann. Mag. Nat. Hist. (7) XIV, p. 90;
Pis. IV, figs. 1, 2 ; V, figs. 15-17.
Bay of Bengal ; 678 fathoms.
In addition to the characteristic verticillated abactinal spines, Mortensen
points out the small actinal and abactinal systems as features in which this
species differs from placenta ; thus the abactinal system of a, placenta, 66 mm.
h. d., is about 30 % h. d., while in verticillatum, 63 mm. h. d., it is only about
20. The color of verticillatum may prove to be a good character, for although
the specimens are bleached, there is some indication of violet actinally, not a
common color in the genus.
Phormosoma rigidum A. Ag.
Phormosoma rigidum A. Agassiz, 1881. " Challenger " Ech., p. 104 ; PI. XHa, figs. 1-4-
Off New Zealand ; 700 fathoms.
Although the specimens on which this species is based are small, the
largest only 40 mm. h. d., the abactinal ambulacral pores are quite charac-
teristic, and we do not think they can wisely be referred to either placenta
or bursarium
Phormosoma adenicum Dod.
Phormosoma adenicum Doderlein, 1905. Zool. Anz. XXVIII, p. 621. 1906. Ech. d.
deutschen Tiefsee-Exp., Pis. XV, figs. 3, 3a ; XXXVIII, figs. 4a-h.
Gulf of Aden ; 816 fathoms.
In addition to the characters given above, this species has an unusual
number of abactinal ambulacral plates, in comparison with the number of
abactinal interambulacral plates. Thus, in Dbderlein's larger specimen
(55 mm. h. d.) there are 17 ambulacral and 10 interambulacral plates abac-
tinally, while in placenta of the same size there are 10-15 and 7-11 respec-
tively ; in adenicum, the abactinal interambulacral plates are less than .60
of the ambulacral, while in placenta they are .70— .75. Possibly the color may
be a good specific character, for Doderlein says his specimens appear to have
been dark red.
PHORMOSOMA INDICUM. 157
Phormosoma placenta Wyv. Thom.
Phormosoma placenta Wyville Thomson, 1872. Proc. Roy. Soc. Edinburgh, VII, 84, p. 617.
1874 "Porcupine" Ech., Trans. Roy. Soc. London, 168, pt. 2, Pis. LXII and
LXIII, figs. 1-8.
North Atlantic, from Davis Strait to Gulf of Mexico on the west and from Iceland to 3° N.
on the east ; 235-1389 fathoms.
This species is so well known, we need add nothing here to the descrip-
tions and figures which have already been published.
Phormosoma Sigsbei A. Ag.
Phormosoma Sigsbei A. Agassiz, 1880. Bull. M. C. Z., VIII, p. 75. 1883. "Blake"
Ech., Mem. M. C. Z., X, Pis. XII; XV, figs. 3-19.
Eastern Caribbean Sea ; 120-573 fathoms.
This species is in life reddish-orange, pinkish abactinally ; preserved
specimens are decidedly pinkish-purple when not bleached. Wyville Thom-
son says placenta is gray flecked with purple ; preserved specimens are
yellowish-brown, sometimes very dark, often more or less bleached. There
is no doubt that this species lives in shallower water, ordinarily, than does
placenta; the latter is most common at depths ranging from 400 to 1000
fathoms, while Sigsbei is found chiefly between 150 and 400 fathoms. The
difference in temperature range is even more noticeable, for, while placenta
is found only in cold water, 37°-41°, Sigsbei occurs in water ranging from
40° to 63°, but averaging about 50°.
Phormosoma indicum Dod.
Phormosoma indicum Doderlein, 1905. Zool. Anz., XXVIII, p. 621. 1906. Ech. d.
deutschen Tiefsee-Exp., Pis. XV, figs. 1, 2; XXXVIII, figs. 2-2c, 3-Sc.
Indian Ocean, coasts of Africa and Sumatra; 257-543 fathoms.
The large size of the abactinal primary tubercles and areolse is very
notable, as they are nearly or quite twice the diameter of those in placenta
and bursarium. The color of this species is rather variable, ranging from
yellow to dark brown, commonly lighter above than below, and often with a
reddish tinge.
158 HAWAIIAN AND OTHER PACIFIC ECHINI.
Phormosoma bursarium A. Ag.
Phormosoma bursarium A. Agassiz, 1881. " Challenger " Ech., p. 99 ; PI. Xb.
East Indies ; off Japan ; Hawaiian Islands ; 165-1050 fathoms.
Plates 62, fig. 2; 63, fig. 3.
This is the Pacific representative of placenta, and very near it in all
essential characters. The difference in tuberculation of the test abacti-
nally seems to be fairly constant, but certain specimens of the two forms
appi-oach each other very nearly. The color of bursarium appears to be quite
uniformly yellow-brown, though the shade varies a great deal ; some speci-
mens are very dark, while others are bleached almost white ; one of the
latter is very decidedly pink on the actinal surface. This species was taken
by the " Albatross " at the following stations, the specimens ranging from
20 to 110 mm. in diameter :
Station 3884. Between Maui and Molokai, Hawaiian Islands. Bott.
temp. 44°. 284-290 fathoms. Glob. m.
Station 3892. Off north coast of Molokai, H. I. Bott. temp. 42.5°.
328-414 fathoms. Fne. gy. s.
Station 3904. Off north coast of Molokai, H. I. Bott. temp. 43.9°.
295 fathoms. Br. m., s., r.
Station 3957. Vicinity of Laysan Island, H. I. Bott. temp. 53.5°. 173-
220 fathoms. Fne. wh. s.
Station 3988. Off Hanamaulu, Kauai, H. I. Bott. temp. 40°. 165-469
fathoms. Gy. for. s., p.
Station 3994. Off Mokuaeae Islet, Kauai, H. I. Bott. temp. 42.9°.
330-382 fathoms. Fne. gy. s., for.
Station 3997. Off Ukula Point, Kauai, H. I. Bott. temp. 41°. 418-429
fathoms. Fne. gy. s., br. m.
Station 4019. Off Hanamaulu, Kauai, H. I. Bott. temp. 37.8°. 409-
550 fathoms. Gy. s., for., r.
Station 4022. Off Hanamaulu, Kauai, H. I. Bott. temp. 41.° 374-399
fathoms. Co., s., for., r.
Station 4025. Off Mokuaeae Point, Kauai, H. I. Bott. temp. 44.9°.
275-368 fathoms. Fne. gy. s., brk. sh., for.
Station 4087. Off Mokuhooniki Islet, Pailolo Channel, H. I. Bott. temp.
43.6°. 306-308 fathoms. Fne. gy. s.
PHORMOSOMA BURSARIUM. 159
Station 4089. Off Mokuhooniki Islet. Pailolo Channel, H. I. Bott. temp.
43.8°. 297-304 fathoms. Fne. gy. s.
Station 4091. Off Mokuhooniki Islet, Pailolo Channel, H. I. Bott.
temp. 43.8°. 306-308 fathoms. Fne. gy. s.
Station 4110. Off Lae-o Ka Laau Light, Molokai, H. I. Bott. temp.
40.3°. 449-460 fathoms. Gy. s.
Station 4111. Off Lae-o Ka Laau Light, Molokai, H. I. Bott. temp.
40°. 460-470 fathoms. Fne. s., r.
Station 4112. Off Lae-o Ka Laau Light, Molokai, H. I. Bott.
temp. 40.5°. 433-447 fathoms. Fne. s.
Station 4113. Off Lae-o Ka Laau Light, Molokai, H. I. Bott.
temp. 40.6°. 395-433 fathoms. Co., for., s.
Station 4141. Off Hanamaulu, Kauai, H. I. Bott. temp. 41°. 437-
632 fathoms. Vol. s., for.
Station 4906. Southwest of Koshika Islands, Japan; 31° 39' N., 129°
20' 30" E. Bott. temp. — 369-406 fathoms.
Station 4907. Southwest of Koshika Island ; 31° 39' 30" N., 129°
24' E. Bott. temp. 42.6°. 406 fathoms. Gy. glob. oz.
Station 4911. Southwest of Koshika Islands; 31° 38' 30" N., 129°.
19' E. Bott. temp. 41.9°. 391 fathoms. Gy. glob. oz.
Station 4912. Southwest of Koshika Islands ; 31° 39' 40" N., 129°
20' E. Bott. temp. 41.9°. 391 fathoms. Gy. glob. oz.
Station 4913. Southwest of Koshika Islands ; 31° 39' 10" N., 129°
22' 30" E. Bott. temp. 41.9°. 391 fathoms. Gy. glob. oz.
Station 4914. Southwest of Koshika Islands ; 31° 33' N., 129° 26'
30" E. Bott. temp. 41.9°. 427 fathoms. Gy. glob, oz., brk. sh.
Station 4915. Southwest of Koshika Islands; 31° 31' N., 129° 25'
30" E. Bott. temp. 41.9°. 427 fathoms. Gy. glob, oz., brk. sh.
Station 4957. Between Kagoshima and Kobe, Japan ; 32° 36' N.,
132° 25'E. Bott. temp. 39.8°. 437 fathoms. Gn-br. m., fne. gy. s., for.
Station 4968. Between Kobe and Yokohama ; 33° 24' 50" N., 135°
38' 40" E. Bott. temp. 45.7°. 253 fathoms. Dk. gy. s., br. m.,
brk. sh.
Station 4969. Between Kobe and Yokohama; 33° 23' 40" N., 135°
33' E. Bott. temp. 38.9° 587 fathoms. Br. m., s., st.
Station 5078. Off Omai Saki Light, Japan ; 34° 12' 20" N., 138°
2' 30" E. Bott. temp. 38.9°. 475-514 fathoms. Fne. gy. s., glob.
160 HAWAIIAN AND OTHER PACIFIC ECHINI.
Station 5082. Off Omai Saki Light ; 34° 5' N., 137° 59' E. Bott.
temp. 37.7°. 662 fathoms. Gn. m., fne. s., glob.
Station 5084. Off Omai Saki Light ; 34° N., 137° 49' 40" E. Bott.
temp. 36.8°. 918 fathoms. Gn. m., fne. s., glob.
Station 5086. Sagami Bay, Hondo Island, Japan ; 35° 8' 15" N.,
139° 20' E. Bott. temp. 43.7. 292 fathoms. Gn. m., crs. bk. s.
Station 5088. Sagami Bay; 35° 11' 25" N., 139° 28' 20" E. Bott.
temp. 41.8°. 369-405 fathoms. Gn. m.
Bathymetrical range, 165-918 fathoms. Extremes of temperature,
53.5°-36.8°.
One hundred and eighty-four specimens.
Echinosoma.
Pomel, 1883. Class. Me'th. Ech., p. 108.
Type-species, Phormosoma tenue A. Agassiz, 1879. Proc. Am. Acad., XIV, p. 202.
(Including Hygrosoma and Tromikosoma Mortensen.)
In this genus, the thin and flexible test has the larger spines and areolae
on the actinal side, but the contrast with the abactinal is not marked. The
hoofs of the actinal primaries are usually large and shining white. The
sphaeridia are more or less elongated and are present only on the inner
(lower) secondary plate-element. Although it is not difficult to distinguish
the genus from the preceding, the species of which it is composed are ex-
ceedingly hard to diagnose in such a way as to make them generally
recognizable. No less than 11 different forms have been described and
named which certainly belong in Echinosoma, but some of these are of
doubtful standing. We are unable to distinguish mordens de Meij. from
tenue A. Ag., or (nthiopicum Dod. from luculentum A. Ag. Doderlein himself
says that the latter is "sehr nahe " cethiopicum, but he distinguishes them
by means of the stout, broad-valved, tridentate pedicellariae which are pres-
ent in luculentum and wanting in cethiopicum. In view of the fact that the
presence or absence of a given form of pedicellariae has been shown, in
numerous cases, to be a matter of individual diversity only, we cannot
consider cethiopicum a valid species. Moreover, hispidum and zealandice
are very near tenue, and panamense and Petersii are very near uranus.
Finally, the line between hoplacantha and luculentum is not as sharp as
could be wished. There seems little reason to doubt that hoplacantha,
ECHINOSOMA HOPLACANTHA. 161
tenue, and uranns are good species, but the others herein recognized are
of less certain validity. The nine accepted species are to be distin-
guished from each other as follows :
Tube-feet abactinally in three series; valves of large tridentate pedi-
cellaria; strongly involute at middle.
Abactinal anibulacral plates only two or three times as numerous
as actinal; abactinal spines small and numerous hoplacantha.
Abactinal anibulacral plates four-seven times as numerous as acti-
nal; abactinal primaries long and conspicuous, secondaries and
miliaries few lucidcntum.
Tube-feet abactinally in one or two series.
Abactinal surface sparsely covered with spines, rarely more than
two primary or large secondary tubercles on a plate ; second-
aries and miliaries not abundant.
Abactinal coronal plates rather high, 11-14 in a specimen 125 mm.
h. d.; tridentate pedicellarise with slightly involuted valves hispidum.
Abactinal coronal plates lower and more curved, 14—16 in speci-
mens 100-125 mm. h. d. ; valves of tridentate pedicellarise
not involute at all tenue.
Abactinal surface more or less thickly covered with spines, often
three or more large tubercles on a plate ; secondaries and
miliaries often abundant.
Ambulacra distinctly broader than interambulacra. . . . KcehlerL
Ambulacra not broader than interambulacra.
Actinostome very large, exceeding .35 h. d., with deep buccal
slits zealandiae.
Actinostome not so large, buccal slits slight.
Whole test thickly tuberculated ; actinal primary tu-
bercles rather small, in vertical series of 6-8 extend-
ing nearly to actinostome panamense.
Test not so thickly tuberculated ; actinal primary
tubercles in vertical series of 3-6, confined to
peripheral half of actinal surface.
Valves of tridentate pedicellarise rather flat, not
involute near middle uranus.
Valves of tridentate pedicellarise strongly involute
at middle, and more or less curved Petersii.
Echinosoma hoplacantha A. Ag. and CI.
Phormosoma hoplacantha Wyville Thomson, 1877. Voy. "Challenger," Atlantic, I,
p. 148.
Phormosoma hoplacantha A. Agassiz, 1881. "Challenger " Ech., Pis. XI ; XII; Xlla,
figs. 10-13.
Hygrosoma hoplacantha Mortensen, 1903. " Ingolf " Ech., I, p. 59.
Pacific and Indian Oceans ; 402-1375 fathoms.
This is not only one of the largest (312 mm. h. d.) of the Echinothuridce,
but it is one of the most easily recognized for the numerous, slender spines
n
162 HAWAIIAN AND OTHER PACIFIC ECHINI.
of the abactinal surface, with primary spines in the ambulacra nearly or
quite to the ocular plates, combined with the three distinct rows of abactinal
tube-feet, give it a characteristic appearance. The color of the test is dark
violet, sometimes with a reddish cast, the spines are dark, often almost black,
but the hoofs are pure white. The specimen collected by the " Valdivia "
and described by Doderlein differs so much in color from the usual condition
that one cannot avoid the suspicion that it may not be this species, and
a careful comparison of the photographs given with Japanese specimens
of JioplacantJia strengthens this feeling. Doderlein is doubtful whether de
Meijere's Jioplacantha is not rather cethiojricum, as he thinks the pedicellariae
figured are nearer the latter species. After examination of Doderlein's
photographs, de Meijere's drawings, and numerous pedicellariae, we find
ourselves driven to this conclusion, — many specimens have some very large
pedicellarise (A. Agassiz, 1881, "Challenger" Ech., PL XLI1I, fig. 1;
Doderlein, 1906, " Valdivia " Ech., PL XXXIX, fig. 3d), and these specimens
all writers call Jioplacantha ; other specimens, equally well preserved, do not
have such large pedicellariae, but do have very short, stout ones, with widely
expanded valves (A. Agassiz, 1. c, PL XLIV, figs. 25, 26 ; Doderlein, 1. c,
PL XXXIX, fig. la), and these specimens are called luculentum. Other
equally good specimens have neither of these characteristic forms, and these
specimens de Meijere calls Jioplacantha, and Doderlein, wthiopicum. For our
part, we consider the absence of either of these characteristic pedicellariae as
a matter of individual diversity and not a specific character, and we
therefore believe de Meijere's identification is correct. Doderlein considers
de Meijere's figure 159 ("Siboga" Ech., PL XIII) more like the valve of a
large tridentate pedicellaria of cethiopicum, than it is like one of Jioplacantha,
but it seems to us that de Meijere's outline sketch is quite as near
Doderlein's figure 3a (1. c, PL XXXIX) as it is to his figure 2c.
This species was taken by the " Albatross " at the following stations, the
specimens ranging from 20 to 170 mm. in diameter :
Station 4928. In Colnett Strait, Japan ; 29° 51' N., 131° 2' 30" E.
Bott. temp. 36.8°. 1008 fathoms. Gy. s. glob.
Station 4956. Between Kagoshima and Kobe, Japan ; 32° 32' N., 132°
25' E. Bott. temp. 37.5°. 720 fathoms. Gn.-bn. m., fne. gy. s., for.
Station 4957. Between Kagoshima and Kobe, Japan ; 32° 36' N., 132°
23' E. Bott. temp. 39.8°. 437 fathoms. Gn.-bn. m., fne. gy. s., for.
Station 4958. Between Kagoshima and Kobe, Japan ; 32° 26' 20" N.,
ECHINOSOMA LUCULENTUM. 163
132° 24' 30" E. Bott. temp. 40.1°. 405 fathoms. Gn.-bn. m., fne. gy. a.,
for.
Station 4973. Between Kobe and Yokohama, Japan ; 33° 24' 15" N.,
135° 30' 30" E. Bott. temp. 38.2°. 600 fathoms. Bn. m., st.
Station 4980. Between Kobe and Yokohama, Japan ; 34° 9' N., 137° 55'
E. Bott. temp. 39°. 507 fathoms. Bn. m., fne. s., for.
Station 5078. Off Omai Saki Light, Japan ; 34° 12' 20" N, 138° 2' 30"
E. Bott. temp. 38.9°. 475-514 fathoms. Fne. gy. s., glob.
Station 5080. Off Omai Saki Light, Japan ; 34° 10' 30" N., 138° 40' E.
Bott. temp. 38.7°. 505 fathoms. Fne. gy. s., glob.
Station 5082. Off Omai Saki Light, Japan ; 34° 5' N., 137° 59' E.
Bott. temp. 37.7°. 662 fathoms. Gn. m., fne. s., glob.
Station 5084. Off Omai Saki Light, Japan ; 34° N., 137° 49' 40" E.
Bott. temp. 36.8°. 918 fathoms. Gn. m., fne. s., glob.
Station 5086. Sagami Bay, Japan ; 35° 8' 15" N., 139° 20' E. Bott.
temp. 43.7°. 292 fathoms. Gn. m., crs. bk. s.
Bathymetrical range, 292-1008 fathoms. Extremes of temperature,
43.7°-36.8°.
Thirteen specimens.
Echinosoma luculentum A. Ag. and CI.
Fhormosoma luculenta A. Agassiz, 1879. Proc. Am. Acad., XIV., p. 201.
Phormosoma luculentum A. Agassiz, 1881. " Challenger " Ech., p. 97; Pis. IX; X; Xa,
figs. 3-7.
Hygrosoma luculentum Mortensen, 1903. " Ingolf " Ech., I, p. 59.
Hygrosoma asthiopicum Doderlein, 1905. Zool. Anz. XXVIII, p. 621. 1906. Ech. d.
deutscheu Tiefsee-Exp. Pis. XVI ; XVII, fig. * ; XXXIX, figs. l-2f.
We are so fortunate as to have before us a small specimen of cethiopieum
from " Valdivia " Station 246. A careful examination of this specimen, in
connection with Doderlein's description and figures, leads us to believe that
the form cannot properly be distinguished from luculentum, for as already
stated we do not consider the absence of the short, thick pedicellarise a valid
specific character. We are even suspicious of the validity of luculentum
itself, for we shall not be surprised if this species proves to be simply a form
of hoplacantha. The differences that have been pointed out in either the
test or the pedicellarite do not seem to us very weighty, and their constancy
has yet to be proven.
164 HAWAIIAN AND OTHEE PACIFIC ECHINI.
Echinosoma hispidum Mortens.
Phormosoma hispidum A. Agassiz, 1898. Bull. M. C. Z. XXXII, p. 77. 1904. Panam.
Deep-Sea Ech., Mem. M. C. Z., XXXI, Pis. XXX-XLIX.
Echinosoma hispidum Mortensen, 1907. " Ingolf " Ech., Pt. II, p. 24.
Gulf of Panama, west to the Galapagos Islands and north to the Gulf of California ;
995-1421 fathoms.
Plates 62, fig. 3; 63, fig. 4; 67, figs. b-11.
The pedicellariae of this species are numerous and variable, but we
have found only tridentate and triphyllous ones, no ophicephalous. Mor-
tensen (" Ingolf " Ech., II, p. 25) says he has found " a kind of ophi-
cephalous pedicellariae." Examination of several good specimens, with
hundreds of pedicellariae, has not enabled us to find this form, so we
conclude it must be quite exceptional. The triphyllous pedicellariae are
abundant and not peculiar, though the neck may be twice or three times
as long as the head (PI. 67, fig. 10), and the stalk three or four times as
long as the neck ; the valves are .40-.50 mm. long and the width at the
tip is rather more than half the length.
The tridentate pedicellariae appear in at least four different forms, but
they integrade with each other to such an extent it is not easy to draw
lines between them. The largest ones (PI. 67, fig. 4) are tolerably com-
mon; the valves (fig. 5) are 3-4.75 mm. long, slightly curved, widened at
tip, and meet only for the terminal quarter ; the edges of the blade are
slightly involute, while the centre is occupied by more or less of a cal-
careous mesh-work. The stalk of these pedicellariae is scarcely as long as
the head, and there is almost no neck. A more abundant form of tri-
dentate pedicellaria is decidedly smaller (PI. 67, fig. 6), has the stalk two
or three times as long as the head and there is a short neck ; the valves
(fig. 7) are straight, 1-1.75 mm. long, not widened at tip or involute at
sides, and meet for their whole length. In another form (PL 67, fig. 8), which
seems to be very rare, the valves are narrow, nearly straight, a trifle
widened at tip, and meet for about three-fourths of their length. They
are 1-1.25 mm. long. A fourth form (PI. 67, fig. 9), which is also rare,
is the smallest of all, but has a long, thick neck and a stalk three to five
times as long as the head ; the valves are only .35— .75 mm. long, straight,
somewhat expanded at tip, and meet for nearly their entire length.
The sphceridia (PL 67, fig. 11) are slightly elongated and seem to be
ECHINOSOMA TENUE. 165
most abundant near the ambitus, though they may occur far up on the
abactinal surface. The calcareous particles in the tube-feet are small and
not very abundant, irregular, perforated plates.
Echinosoma tenue Pomel.
Fhormosoma tenuis A. Agassiz, 1879. Proc. Am. Acad., XIV, p. 202.
Phormosoma tenue A. Agassiz, 1881. "Challenger" Ech., p. 91; Pis. XIII, XIV, et al.
Echinosoma tenue Pomel, 1883. Class. Meth. Ech., p. 108.
Pacific Ocean; 1875-2750 fathoms.
Plate 67, figs. 12-21.
The specimens before us, collected by the " Albatross," show that unless
there is some mistake in the labels, this species has an astonishing bathy-
metrical range. We have compared most carefully the specimens from
Stations 3784, 4928 and 5084 with one of the co-types of tenue from " Chal-
lenger" Station 237, and we find they agree so perfectly in all details that it
is impossible to doubt their identity. The specimen from 3707, on the other
hand, is small (about 30 mm. h. d.) and more or less damaged, and the origi-
nal label has the station number so faint that it has been repeated in lead
pencil, and in this repetition there is chance for error ; Stations 3710, 3711,
3712, and 3736 were the only Japanese stations occupied by the " Alba-
tross" in 1900 where this species would be expected to occur. This small
specimen has the tube-feet arranged as in tenue, so far as they can be made
out, and the pedicellarige, so far as may be judged from a very few exam-
ples, are like those of tenue. We therefore believe that the identification
of the specimen is correct, but we do not believe it was taken at Station
3707. The color of the specimens before us is varied; the "Challenger"
specimen is yellowish, with strong indications of violet actinally, and has
light-colored tube-feet ; one of the specimens from 3784 is also somewhat
yellowish, especially abactinally, but the tube-feet are dark violet in strik-
ing contrast ; the other specimens range from light to dark violet without
a trace of yellow on the test, but in some cases the tube-feet are brownish-
yellow. The color of both test and feet seems to depend on the extent
to which the bright violet pigment is developed.
The arrangement of the tube-feet, abactinally, in tenue, is characteristic
when well marked, but there is some individual diversity. In the " Chal-
lenger " specimen there are two series closely approximated to each other,
on each side of the ambulacrum ; in the outer series there are practically
1G6 HAWAIIAN AND OTHER PACIFIC ECHINI.
twice as many feet as in the inner, each foot in the latter series being
opposite alternate feet in the former ; in the inner series, small primary
or large secondary tubercles alternate with the feet, so that, while the
outer series consists of feet only, the inner consists of alternating tuber-
cles (spines) and feet. In the specimens from 3784 this arrangement is
very evident, but it is not quite so clear as in the "Challenger " specimen,
because the feet are larger and nearer together vertically. In the speci-
mens from 4928 and 5084, it is not at all noticeable, because the tube-feet
are small, light colored, and rather far apart vertically.
The pedicellariae of tenue are not very characteristic, for while they
show no little diversity, no one form is really distinctive. Ophicephalous
pedicellariae are numerous on the abactinal surface just above the ambitus
in one of the specimens from 4928 and in one of those from 5084 ; a few
were also found in the second specimen from 4928 and one in the second
(smaller) specimen from 5084 ; in the " Challenger " specimen and in the
two fine individuals from 3784 there are none. The occurrence of ophi-
cephalous pedicellariae seems to be, therefore, an individual and not a specific
character. Tridentate and triphyllous pedicellariae are abundant and more
or less variable.
The triphyllous pedicellariae (PI. 67, fig. 19) have very slender stalks, with
the neck of variable length, usually several times as long as the head.
The valves (PI. 67, figs. 15, 20) are rather broad, about half as wide at
the tip as they are long, or a little wider ; they are usually somewhat trun-
cate at the tip, but those on the specimens from 3784 are often more
rounded (fig. 15) ; they are about half a millimeter long.
The tridentate pedicellariae (PI. 67, figs. 12, 17) vary greatly in size and
more or less in form. In the larger ones the neck is short and the stalk
is only a little longer than the head, while in the smaller ones the neck
may equal the head and the stalk be several times as long. In the largest
the valves (PI. 67, figs 13, 16) may be 2.5 mm. long ; they are straight,
usually meet for their full length, and the sides of the blade are more or
less nearly parallel and not at all involute; the blade is more or less filled
with a calcareous mesh-work, and the apophysis usually extends into the
blade as a serrate median ridge. In the specimens from 3784 the
large pedicellariae are quite variable, and in many of them the valves are
separate at the base (see PI. 67, fig. 12) for a greater or less distance ;
the valves are also more or less constricted at the base of the blade and
ECHINOSOMA KCEHLERI. 167
the apophysis fails to extend into it (fig. 13). The smaller tridentate
pedicellariaj are not peculiar; the valves (PI. 67, figs. 14, 18) are about .40
mm. long and closely in contact throughout, usually they are more or less
pointed (fig. IS), but many of those on the specimens from 3784 are
rounded (fig. 14). Perhaps it ought to be emphasized that the tridentate
pedicellariaj integrade with each other in form as well as in size, and the
specimens from 3784 have the ordinary forms as well as the more unusual
forms figured.
The op/ricejihahus pedicellariaB resemble those of Sperosoma. The stalks
are very long, five or six times as long as the head, straight and rela-
tively stout. There is almost no neck. The valves (PI. 67, fig. 21) are
about .70 mm. long, strongly constricted near the middle and have large
articulating loops.
This species was taken by the " Albatross " at the following stations, the
specimens ranging from 30 to 135 mm. in diameter.
Station 3707 (?). Off Ose Zaki, Honshu Island, Japan. 63-75 fathoms.
Vol. s., a., g.
Station 3784. North of Aleutian Islands; 54°32'N., 178° 3PE. 850
fathoms.1 Gn. m., fne. gy. s.
Station 4928. In Colnett Strait, Japan ; 29° 51' N., 131° 2' 30" E. Bott.
temp. 36.8°. 1008 fathoms. Gy. s., glob.
Station 5084. Off Omai Saki Light, Japan; 34° N., 137° 49' 40" E.
Bott. temp. 36.8. 918 fathoms. Gn. m., fne. s., glob.
Bathymetrical range, 63-1008 fathoms; probably 850-1008 fathoms is
correct.
Eight specimens.
Echinosoma Kcehleri A. Ag. and Cl.
Tromikosoma Kcehleri Mortensen, 1903. " Ingolf " Ech., I, p. 78 ; figs. 5, 6.
Davis Strait, 1435 fathoms.
In addition to the extraordinary width of the ambulacra, the abactinal
arrangement of the tube-feet is an interesting character of this species ; for
the inner series contains twice as many feet as the outer, just the reverse of
the condition found in tenue.
1 The depth as published in the " Albatross " Records is 85 fathoms. But on the label with these
specimens, it is distinctly " 850 fins." The " 85 " is doubtless a misprint.
168 HAWAIIAN AND OTHER PACIFIC ECHINI.
Echinosoma zealandiae A. Ag. and Cl.
Phormosoma zealandiae A. Agassiz, 1904. Panam. Deep-Sea Ech., Mem. M. C. Z.,
XXXI, p. 105 ; PI. LI, figs. 1-4.
Off New Zealand ; 700 fathoms.
As the specimen on which this species is based is extremely young (24
mm. h. d.), it is difficult to differentiate it clearly from the other members of
the genus. Like Phormosoma rigidum, from the same station, it must await
further material before having its true status determined beyond doubt.
Echinosoma panamense Mortens.
Phormosoma panamense A. Agassiz, 1898. Bull. M. C. Z., XXXII, p. 77. 1904. Panam.
Deep-Sea Ech., Mem. M. C. Z., XXXI, p. 101 ; figs. 145-US.
Echinosoma panamense Mortensen, 1907. "Ingolf" Ech., II, p. 24.
Off Gulf of Panama; 1823 fathoms.
Plate 67, figs. 1-3.
The pedicellarioe of this species are remarkably short and stout and show
little diversity of form.
The tridentate pedicellarise (PL 67, figs. 2, 3) are all of essentially the
same structure, but differ considerably in size. Mortensen (" Ingolf " Ech.
II, p. 24) says he has not found the large form of tridentate pedicellaria in
panamense ; as we have also failed to find this form, it probably does not
occur in this species. The form which is common, has very wide valves,
rounded or bluntly pointed at the tip, in contact for their whole length ;
the necks are longest in the small ones and may be very short in large
ones ; the stalk only equals the head in large ones, but is four or five times
as long as the head in small ones. The valves range from .35 to 1 mm. in
length, and the width is two-thirds of the length or even more. In form
the valves are almost exactly like those of the Echinothurid which we have
called Sperosoma biseriatum (see PI. 65, fig. 18), but the blade is often wider
at the tip, the sides being nearly parallel.
The triphyllous pedicellaria3 (PI. 67, fig. 1) are common and show little
diversity. The stalk is about four times as long as the neck and the latter
is equal to, or usually exceeds, the head. The valves are like that shown
on Plate 65, fig. 19.
The calcareous particles in the tube-feet are perforated plates of varying
size and form, but in general like those shown on Plate 65, fig. 20. They
are commonly larger and more abundant than in hispidum.
KAMPTOSOMA. 169
Echinosoma uranus Pomel.
Phormosoma uranus Wyville Thomson, 1877. Voy. " Challenger," Atlantic, p. 146 ;
figs. 33, 34.
Echinosoma uranus Pomel, 1883. Class. Meth. Ech., p. 108.
North Atlantic, 1000-15-25 fathoms.
The difference between the tridentate pedicellarioe of this species and
the next is marked and can be easi]y detected with a hand lens, but whether
it constitutes a specific difference seems to us open to question. Aside from
the characteristic pedicellarise, this species is very near the following and we
shall not be surprised if further material proves that the two are identical.
Echinosoma Petersii A. Ag. and Cl.
Phormosoma Petersii A. Agassiz, 1880. Bull. M. C. Z., VIII, p. 76. 1883. " Blake "
Ech., Mem. M. C. Z., X, Pis. X, XL
Hygrosoma Fetersu Mortensen, 1903. " Ingolf " Ech., I, p. 59.
North Atlantic, particularly Caribbean region ; 647-1224 fathoms.
As stated above, we are not wholly satisfied as to the validity of this
species, but are inclined to let it stand for the present. Mortensen (op. cit.,
p. 59) says that the tube-feet abactinally are in " three series very close
together." Plate X and Plate XT, fig. 1, of the " Blake " Echini seem to
confirm the statement. The true condition is shown in Plate XI, fig. 5,
of the " Blake " report, where it will be seen that the arrangement really
is in two series. When a specimen is compared with hojjlacaniha and tcnue,
it is obviously nearer tenue, but in large specimens, the feet may become so
crowded that the tendency towards three series is evident.
Kamptosoma.
Mortensen, 1903. "Ingolf" Ech., I, p. 60.
Type-species, Phormosoma asterias A. Agassiz, 1881. " Challenger " Ech., p. 104.
The rather thin and delicate test has the actinal side quite different from
the abactinal in the form of the plates but not in the size of spines or
tubercles. Few of the primary ambulacral plates are accompanied by sec-
ondary plate elements and never by more than a single one. The sphasridia
are carried on the primary plates actinally but may be on secondary plates
abactinally. The stalk of the pedicellarias is made up of loosely connected
calcareous threads. This remarkable genus appears to be confined to the
deep parts of the southern Pacific Ocean, having been met with hitherto
170 HAWAIIAN AND OTHER PACIFIC ECHINI.
only by the " Challenger." Its relationship to the other Echinothuridoe is
still unsettled and more material is greatly to be desired. There is an
interesting parallelism between this genns and Micropyga in the struct-
ure of the stalks of the pedicellariae ; each is the only genus in its family
with these stalks noticeably different in structure from those found in
the allied genera.
There appear to be two quite distinct species of Kamptosoma which
may be separated from each other as follows :
Abactinal ambulacral areas not noticeably expanded just above ambitus,
composed of high plates not wider than those of the actinal side,
their width not exceeding twice their height and sometimes not
equalling it asterias.
Abactinal ambulacral areas markedly expanded just above ambitus,
composed of low plates, much wider than those of the actinal
side, their width often four times the height indistinctum.
Kamptosoma asterias Mortens.
Phormosoma asterias A. Agassiz, 1881. "Challenger" Ech., p. 104 ; PI. XID, figs. 7-9.
Kamptosoma asterias Mortensen, 1903. " Ingolf " Ech., p. 60.
Off the coast of Chili; 2160 fathoms; "Challenger" Station 299.
The type-specimen of this interesting species, 30 mm. in diameter and
doubtless young, is still unique.
Kamptosoma indistinctum A. Ag.
Kamptosoma indistinctum A. Agassiz, 1904. Panam. Deep-Sea Ech., Mem. M. C. Z.,
XXXI, p. 110 ; PI. 50. North of the Society Islands, East of Maiden Island,
2600 fathoms; "Challenger" Station 272.
In spite of Mortensen's decision to the contrary, we think this species
must be maintained, unless the differences of ambulacral structure referred
to above, which distinguish this species from the preceding, can be shown
to be unreliable. We beg to call attention to two facts which bear on
this point. First : it was only in this species that Mortensen found the
large, characteristic tridentate pedicellariae ; they were not found in the
type of asterias. Second : Mortensen says that secondary ambulacral plate
elements are wanting, except " nearest to the peristome a single one may
be found." Unfortunately he does not say whether this was observed in
the type of asterias or in a specimen from " Challenger" Station 272. If in
the former, it gives us an additional specific character; if in the latter,
we are at a loss to reconcile his statement with the real condition in in-
distinctum (see Panam. Deep-Sea Ech., p. Ill, fig. 151 and Plate 50, fig. 3).
ASTHENOSOMA. 171
ASTHENOSOMA.
Grube, 18G8. 45er Jahres-Bericlit d. Schles. Gesell, p. 42.
Type-species, Asthencsoma varium Grube, 1. c.
After careful consideration it has seemed desirable to limit Astheno-
soma, as Mortensen proposed, to the species on which Grube based the
genus and its nearest allies. They are characterized by a rather firm test
having the actinal side markedly different from the abactinal. The coronal
plates of the upper side are very low and wide, each witli a horizontal series
of 5-20 small primary tubercles, none of which are noticeably larger than
the others. The abactinal primary spines are small and numerous, and are
encased in loose skin-sheaths. The actinal tube-feet have well-developed
sucking-discs. The sphteridia are more or less elongated and occur only on
the inner (lower) secondary plate-element. In this limited sense Astheno-
soma includes at most only four species, and probably only two. The evi-
dence accumulated by de Loriol, Dbderlein, and de Meijere seems to prove
that A. Grubei A. Ag. is really a synonym of varium Grube, as Agassiz
himself suggested in 1881 ("Challenger" Echini, p. 84). From the descrip-
tions and figures which have been published we are strongly inclined to
consider A. urens Sarasins and A. heteractis Bedford as also synonyms of
varium, but as we have no material at hand for comparison, we let them
stand for the present as distinct. The following table shows how closely
related the four accepted species are :
Actinal primaries more or less distinctly banded (usually greenish banded
with purple).
Auibulacral primary spines, abactinally, much longer than those of inter-
ambulacra but not markedly unlike them in color.
Naked radial areas of abactinal surface, relatively narrow, or want-
ing ; that of median interambulacral field not exceeding .10 of
interambulacrum rarium.
Naked radial areas of abactinal surface, conspicuous ; that of median
interambulacral field exceeding .20 of interambulacrum .... urens.
Ambulacral primary spines, abactinally, about equal to those of interam-
bulacra, markedly different from them in appearance, the sheaths being
very distinctly and regularly banded with purple heteractis.
Actinal primaries white and unhanded Ijimai.
172 HAWAIIAN AND OTHER PACIFIC ECHINI.
Asthenosoma varium Grube.
Asthenosoma varium Grube, 1868. 45" Jahres-Bericht d. Schles. Gesell., p. 42.
Asthenosoma Grubei A. Agassiz, 1879. Proc. Am. Acad., XIV, p. 200. 1881. " Chal-
lenger " Ech., Pis. XV-XVII.
East Indies. Littoral.
There seems to be no sufficient ground, in the present state of our
knowledge, for regarding varium and Grubei as distinct. It is certainly
to be doubted whether either of the two succeeding forms is really different
from varium.
Asthenosoma urens Saras.
Cyanosoma urens Paul and Fritz Sarasin, 1886. Zool. Anz., IX, p. 80.
Asthenosoma urens Paul and Fritz Sarasin, 1888. Ergeb. Nat. Forsch. Ceylon, I, p. 86 ;
Pis. X-XVII.
Ceylon. Littoral.
It seems very doubtful whether this species is distinguishable from
varium, but further study of fresh material in the East Indies will be neces-
sary before the point can be settled. Attention ought to be called to the
astonishing discrepancy between the Sarasins' colored figure (PL X) and
the photograph given by Doderlein (Semon's Zool. Forsch. Aust., PL LX,
fig. 3) of what he tells us is an " Originalexemplar " of urens from the
Sarasins' collection. It is incredible that this photograph can represent an
animal which had ever had the coloration shown in the Sarasins' figure,
yet strangely enough Doderlein makes no reference to the color. If urens
has the coloration shown by the Sarasins it must be very different from
varium ; while, on the other hand, if Doderlein's figure represents the normal
appearance of urens it must be very near, if not identical with, Grube's
species. The differences described by Doderlein between varium and urens
do not seem to us to be very weighty, and his suggestion that the two
forms are varieties of one species seems quite probable, if they are dis-
tinguishable at all.
Asthenosoma heteractis Bedford.
Asthenosoma heteractis Bedford, 1900. Proc. Zool. Soc. London, p. 278 ; PI. XXI, fig. 2.
Singapore ; 5 fathoms.
We do not consider the characters assigned to this species as of very
great importance, and we are strongly inclined to think that the original
specimens are young examples of varium.
ASTHENOSOMA IJIMAI 173
Asthenosoma Ijimai Yosh.
Asthenosoma Ijimai Yoshiwara, 1897. Ann. Zool. Japon., I, p. 8; PI. II, figs. 8-12.
Asthenosoma Ijimai Mortensen, 1904. Ann. Mag. Nat. Hist. (7) XIV, p. 87 ; Pis. Ill ;
V, figs. 1-3, 10, 12-14.
Sagami Bay, Japan ; 50-55 fathoms.
The arrangement of the tubercles in the interambulacral plates of the
abactinal side of the test in this species resembles closely that of A. varium.
The columns of primary tubercles of the actinal side do not reach beyond
the ambitus, and there is nothing of the characteristic arrangement of the
extension of the primaries toward the abactinal system so striking in many
species of Araeosoma.
Mortensen criticises Yoshiwara's description of the madreporic plate, as
he does not consider the madreporic plate divided, but rather that the
madreporic pores have spread into adjoining plates. In the specimens
before us there seems to be no room to doubt that the madreporic plate is
divided, exactly as Yoshiwara described it, " into four separate pieces of
unequal size, the largest occupying the normal position." In addition
there are a dozen or more very small fragments of the plate, around the
genital opening, distal to the main plate. The madreporic pores spread
into the ocular plates on each side, but chiefly into the one in the right
anterior ambulacrum. The splitting up of the genital plates is now so
well known in the Echinothuridse that the condition of the madreporic
plate in this species, while interesting, is far from exceptional. On the
other hand, the extension of madreporic pores into anal plates is a very
rare phenomenon, never occurring normally so far as we know, so that
we cannot assent to Mortensen's interpretation of the condition in Ijimai.
When he says that the spread of madreporic pores " over the neighboring
plates " is a feature " upon the whole not very seldom occurring among
Echinids," it must be assumed that he means by "neighboring" plates
only genitals and oculars, for the presence of madreporic pores in plates
either inside or outside of the genito-ocular ring is most unusual. In
Ijimai, the plates in question must be either anal plates or parts of the
genital, and we feel no doubt that they are the latter.
174 HAWAIIAN AND OTHER PACIFIC ECHINI.
Ar^osoma.
Mortensen, 1903. " Ingolf " Ech., pt. 1, p. 53.
Type-species, Calreria fenestrate/, Wyville Thomson, 1872. Proc. Roy. Soc. London,
XX, p. 494.
(Including Calveria and Hapalosoma of Mortensen.)
Actinally this genus is not essentially different from Asthenosoma, but
seen from above the difference is quite marked. In Araeosoma none of
the abactinal primary spines are encased in loose skin-sheaths. There
are at least 25-30, and sometimes several hundred, primary tubercles
which are much more conspicuous than the rest and their areolae are cor-
respondingly large. The coronal plates are also much higher than in
Asthenosoma, but the texture of the test varies much in the different species.
This is the largest genus of the family, but although the species show
sonTe tendency to an arrangement in three or four groups, we have failed
to find any satisfactory characters by which such groups may be constantly
distinguished. We can hardly believe that the texture of the test, the
relative width of ambulacra and interambulacra, or the relative number
of ambulacral and interambulacral plates, are any better generic characters,
taken by themselves, than the color or the pedicellarioe. And while by using
any one of these characters we might arbitrarily establish several " genera,"
they would intergrade so completely in their other characters, we do not
think such subdivisions would be either natural or desirable. Accepting
Mortensen's view that A. Reynoldsii A. Ag. is a synonym of fenestration
Wyv. Thorn., and A. hngispinum Yosh. is identical with A. gracile A. Ag.,
we still recognize 14 species of Araeosoma. They show great diversity in
color, texture of the test, distribution of primary spines, relative number of
ambulacral and interambulacral plates, relative width of ambulacra and
interambulacra, length of spines, and form of pedicellarioe ; and it is surpris-
ingly hard to distinguish them from each other, for not only do their
characters reveal more or less individual diversity, but they intermingle
most perplexingly in the different forms. We have reached the conclusion
that color is often a good character in this genus, and it proves to be of
considerable service in distinguishing certain species. The form of the
valves of the large tridentate pedicellarioe, which can be easily seen with
an ordinary lens, is also a useful character, even if we cannot follow
Mortensen in making it generic. The width of the ambulacra and the
number of ambulacral plates are valuable, within certain limits, but age
differences need to be guarded against, and the same is true of the spines
AR^EOSOMA 175
and primary tubercles. Only rarely is the relative size of the actinostome
or abactinal system of any importance, but the relative amount of calci-
fication of the coronal plates and the degree to which they are bent adorally
are often very useful characters. The species which seem to us probably
valid may be distinguished as follows :
Actinal primary tubercles not forming an uninterrupted marginal series at
ambulacral edge of each half-interambulacrum, since some inter-
ambulacral plates (usually every other one, at least near ambitus)
do not have a primary tubercle at extreme outer end.
Abactinal primary tubercles fewer than 100, nearly or quite as large as
those of actinal surface thetidis.
Abactinal primary tubercles more than 200, much smaller than those of
actinal side bicolor.
Actinal primary tubercles forming an uninterrupted marginal series at
ambulacral edge of each half-interambulacrum, since each inter-
ambulacral plate has a primary tubercle at its extreme outer end.
Ambulacra very narrow, about .40 of interambulacra ; primary spines
near ambitus banded with red or reddish-purple pellucidum.
Ambulacra more than half as wide as interambulacra ; primary spines
not banded.
Ambulacra very broad, more than .75 of interambulacra.
Ambulacra .90 of interambulacra; interambulacral plates
much more numerous abactinally than actinally, strongly
inclined (near ambitus, curved) towards mouth, those at
ambitus with inner end so much more adoral than outer,
that the plate is 30 per cent longer than one-half the width
of interambulacrum eurypatum.
Ambulacra .80 of interambulacra; interambulacral plates
nearly as numerous actinally as abactinally, more or less
oblique, but even at ambitus their length is only about 10
per cent longer than one-half the width of interambu-
lacrum leptaleum.
Ambulacra moderately broad, .50-.75 of interambulacra.
Entire test bright red, the color more or less well-preserved
in alcoholic and dry specimens; large tridentate pedi-
cellarise with curved valves having the blade strongly
involute except at tip.
Test bright rose-red; actinostome about .25 h. d.; few ac-
tinal interambulacral plates with two or more primaries hystrix.
Test bright vermilion ; actinostome less than .20 h. d. ;
most actinal interambulacral plates with two or more
primaries pyrochloa.
Test never bright red; colors variable, the actinal and
abactinal surfaces often different ; colors usually more
or less bleached or altered in preserved specimens.
Ambulacral plates rather high and few, interambulacral
about four-fifths as many ; test reddish-purple above,
lighter, often yellowish, beneath Belli.
176 HAWAIIAN AND OTHER PACIFIC ECHINI.
Ambulacral plates low and numerous, interambulacral
only three-fifths — three-fourths as many.
Color uniform dark violet ; actinal primary spines
(except hoofs) equally dark violaceum.
Color never uniformly dark violet ; actinal primary
spines usually lighter than test.
Coronal plates, especially abactinally, with wide
interspaces of leathery skin.
Abactinal interambulacral plates strongly
curved or bent adorally so that their ex-
panded inner ends are much nearer mouth
than the outer ends, in large specimens as
much as 15 mm. nearer coriaceum.
Abactinal interambulacral plates nearly or
quite straight, though they are not neces-
sarily horizontal tessellatum.
Coronal plates with small interspaces or none.
Number of ambulacral plates abactinally lit-
tle or not at all exceeding actinal number fenestration.
Ambulacral plates abactinally 50-60 per
cent more numerous than actinally.
Test thin ; valves of large tridentate pedi-
cellariaB curved, with blades strongly
involute except where they meet at tip gracile.
Test rather stout ; valves of large triden-
tate pedicellariffi straight or nearly
so, the blades not involute but in con-
tact for most of their length . . . Owstoni.
Arseosoma thetidis A. Ag. and Cl.
Asthenosoma thetidis H. L. Clark, 1909. Bull. M. C. Z., LII, p. 134.
Off Botany Bay, New South Wales ; 80 fathoms.
Plates 66, figs. 6-17; 68-70.
Although at first sight this species appears to be closely related to
A. Owstoni Mort., careful examination reveals some very decided differences,
particularly on the actinal surface. The largest specimen before us meas-
ures 180 mm. in diameter; the interambulacra are 63 mm. broad at the
ambitus, while the ambulacra are 46 mm. across in the same region. The
abactinal system is 32 mm. in diameter, while the actinostome is 41 mm.
across. There are 45 coronal plates in each half of an interambulacrum,
of which 18 are below the ambitus. The ambulacral plates number 70 from
the peristome to the ocular plate ; of these 28 are on the actinal side ; there
are 12-14 additional pairs of poriferous plates in each radius of the actino-
stome. The primordial interambulacral plate at the peristome is very
evident (Pis. 69 ; 70, fig. 2) and bears several small primary tubercles.
AILEOSOMA THETIDIS. 177
The other actinal coronal plates each carry one or two primary tubercles ;
these vary greatly in their position on the plate, but as a rule every other
plate has one such tubercle near its outer end and a second near the inner
end ; the alternating plates usually have a single large tubercle at the
middle, but occasionally there are two tubercles present. Sometimes a plate
occurs with no primary tubercles. It will be seen, therefore (PI. 69), that
there is a tendency to form three well-spaced longitudinal series in each half
of the interambulacrum. On the abactinal surface most of the coronal
plates carry no primary tubercles, but six or eight plates in each column
are made conspicuous (PI. 68) by the single large tubercle which each bears.
The inner, imbricating ends of the coronal plates are abactinally quite bare
and perfectly smooth (PL 68), but there is no uncalcified membrane between
the pjates, except for a very small area at the lower margin of about a
dozen plates, beginning with the fifth or sixth from the genital plate.
Actinally the coronal plates are well covered, clear to the median line, with
secondaries and miliaries, but abactinally the margins of each plate are, on
all sides, more or less bare.
Each half-column of an ambulacrum actinally (PI. 69) is made up of very
wide, rather large primary plates, each accompanied by two small secondary
plate-elements. The latter are very little larger than the peripodium which
each bears. Although the tubercles are arranged in two series, on each
side, their distribution is quite irregular. It is rather more common to find
two tubercles on a single plate, one at each end, with the adjoining plates
above and below without tubercles, than to find them alternating, as might
be expected, plates with a tubercle at the inner end succeeding and being
followed by plates with an outer tubercle. Abactinally (PL 68) only five or
six plates in each column bear large tubercles, and these are irregularly
scattered. The remaining surface of the ambulacral plates is fully covered
actinally with secondaries and miliaries, but abactinally the margins of each
plate, especially the outer ends, are quite smooth and bare. The three series
of pore-pairs run rather close together the full length of the ambulacrum ;
even just above the ambitus (PL 70, fig. 4) the outer series (in the primary
plates) is not very widely separated from those in the secondary plates.
The abactinal system (PL 70, fig. 1) is small and well defined. The
genital and ocular plates are not in contact with one another. The genitals
are long, triangular, separating the two upper pairs of plates of each inter-
ambulacrum ; the pores are large, occupying the greater part of the distal
178 HAWAIIAN AND OTHER PACIFIC ECHINI.
half of the plate. The ocular plates are somewhat pentagonal, with very
small pores. The anal system is large, 18 mm. across, and is covered by
several concentric circles of small plates, the inner ones the smallest ; many
of the outer ones carry one or more secondary spines.
The smallest specimen of thetidis which we have is 72 mm. across, with
the actinal system 18 mm., the abactinal system 11 mm., and the anal
system 8 mm. in diameter. The interambulacra are 26 mm. wide at the
ambitus and have 32 plates in each half-column, while the ambulacra are 20
mm. wide and are made up of 43 pairs of plates. The primary tubercles of
the abactinal side are about as numerous as in large specimens and there-
fore appear much more numerous relatively. Actinally they are fewer and
tend to form a regular marginal row along the outer border of each inter-
ambulacrum, a much less regular series at the inner ends of the same plates,
and two very irregular series in the middle of each ambulacrum.
The spines of this species offer no peculiarities and the pedicellaria? are
very much like those of Owstoni and bicolor. We have not found any
" dactylous " ones, however, although careful examination has been made of
several specimens. The tridentate pedicellarire are exceedingly abundant,
particularly just below the ambitus, while the triphyllous are less common.
The tridentate pedicellarise (PI. 66, figs. 15, 17) are extraordinarily diver-
sified in size and form, though on the same general plan. The heads are
thick and blunt, and the stalks are about twice as long as the head or longer.
The valves (PI. 66, figs. 6-12) range in length from one-fifth of a millimeter
to over two millimeters ; they are in contact for nearly their entire length,
except in rare cases, where only the terminal halves touch. In small pedi-
cellariae, the valves have a nearly straight or somewhat convex, smooth
margin, but in the larger ones it is more and more sinuate, until in the
largest it is very coarsely toothed. In all large pedicellariae the blade is
filled with a coarse mesh-work which may rise up into irregular serrate
ridges (PI. 66, figs. 11 and 12) ; in large valves the tip may be very strongly
hooked.
The triphyllous pedicellarice (PI. 66, fig. 16) are not very numerous and
have rather elongated heads on slender stalks; the valves (fig. 17) are
narrow, with a very long, perforated cover-plate, and rounded at the tip.
The calcareous spicules (PI. 66, fig. 13) in the tube-feet are small, irregular, but
essentially triradiate, bodies, sometimes appearing as small perforated plates.
ARJSOSOMA BICOLOR. 179
Arseosoma bicolor A. Ag. and CI.
Asthenosoma bicolor A. Agassiz and Clark, 1907. Bull. M. C. Z., LI, p. 118.
Plates 64, figs. 1-8; 71; 72.
This species, of which only a single specimen was collected, is nearly
related to Owstoni, but differs in color and in certain features of the
test. The coronal plates are low and very numerous, 44 in the inter-
ambulacra and 75 in the ambulacra (Pis. 71, 72, figs. 3, 4) ; in Owstoni
of the same size (125 mm.) the numbers are 38 and 60 respectively.
The test is more flexible abactinally than in Owstoni, and the bare median
ambulacral and interambulacral areas are more marked (PL 71, figs. 1, 2).
The test and spines are dull yellowish actinally, while on the abactinal
surface the interambulacra are chiefly yellow and the ambulacra are dull
violet. These colors are not sharply defined, but contrast with each other
nevertheless. On the actinal side the primary ambulacral tubercles form
two median longitudinal series (PI. 71, fig. 2). At the ambitus there are
two additional series of primaries somewhat smaller which extend irregularly
along the ambulacrum for about two-thirds the distance from the ambitus to
the apex (PI. 71, fig. 1). The actinal primary interambulacral tubercles are
arranged in six very irregular rows ; in the outer rows, adjoining the ambu-
lacral area, they are closely packed (PI. 71, fig. 2) two-thirds of the distance
from peristome to ambitus. On the abactinal surface the primary interam-
bulacral tubercles extend in irregular open rows almost to the apical system
(PL 71, fig. 1). The rest of the plate is closely covered with miliaries (PL 72,
fig. 4). The primordial actinal interambulacral plate is large and prominent
(PL 72, fig. 1). The imbricating actinal plates, in prolongation of the ambu-
lacral series, cover the whole buccal membrane except at the actinal margin
of the interambulacra, where there are a few minute plates (PL 72, fig. 1). The
actinal plates are covered with minute secondaries and miliaries arranged in
horizontal rows.
The genital plates in bicolor are not so elongated as in Owstoni, for they
separate only the first pair of interambulacral plates and touch the second
(PL 72, fig. 2), while in Owstoni they separate the first two pairs and touch,
sometimes nearly separating, the third. In bicolor four of the genital plates
are remarkable in that the outer part of the plate (i. e. the part distal to the
pore) is separated by a regular suture from the remainder of the genital and
180 HAWAIIAN AND OTHER PACIFIC ECHINI.
thus is a perfectly distinct plate (PI. 72, fig. 2). The madreporic genital is
divided into three parts. The anal system is covered with two outer rows of
small irregularly shaped polygonal plates, each carrying a small miliary or
secondary ; close to the anus the membrane is covered by minute elliptical
plates.
The pedicellarise of this species resemble closely those of Oiostoni, but show
some interesting differences.
The dactylous pedicellarice (PI. 64, fig. l) are very scarce and seem to be
confined to the actinal side near the ambitus. The stalk is much longer
than the head. The three valves are about 1.4 mm. long and completely
concealed in the glandular tissue which surrounds them; when cleaned from
this organic matter they are found to be very asymmetrical (PI. 64, fig. b) ;
the blade is greatly compressed for most of its length, but is expanded, with
infolded margins, at the tip, and is more or less abruptly bent below this
expanded tip.
The tridentate pedicellarise (PI. 64, fig. 2) are very abundant and vary
greatly in size and somewhat in form, though the connecting links are
plentiful. The smallest have the valves (PI. 64, fig. 7) about .45
mm. long, very blunt, with nearly parallel, straight sides ; the apo-
physis continues to some extent into the blade. In the largest, the
valves (PL 64, figs. 5, 6) are two and a half millimeters long, narrow,
and more or less closely in contact throughout ; the blade has a very
sinuate margin, and on the convex curves the margin is somewhat in-
folded and rough, with minute teeth (see fig. 6) ; the blade is filled with a
calcareous mesh-work and the apophysis is prolonged as a prominent, serrate
ridge. Between these two extremes all sorts and sizes of tridentate pedicel-
lariae may be found.
The tripliyllous pedicellariae (PI. 64, fig. 3) have very long and slender
stalks and rather long necks ; the valves (fig. 8) are about half a millimeter
long, and like those of t/ietidis and Owstoni have a very extensive, more or
less perforated, cover-plate. The spbceridia and calcareous spicules are not
noteworthy.
This species is based on a single specimen, 125 mm. in diameter, taken by
the " Albatross " at the following station :
Station 4939. Kagoshima Gulf, Japan ; 31° 18' 30" N., 130° 42' E. 85
fathoms. Character and temperature of bottom not recorded.
ARiEOSOMA EURYPATUM. 181
Araeosoma pellucidum A. Ag. and CI.
Asthenosoma pellucidum A. Agassiz, 1879. Proc. Am. Acad., XIV, p. 200. 1881.
"Challenger" Ech., Pis. XVIII, figs. 1-6; XIX, figs. 1-6; etc.
Hapalosoma pellucidum Mortenseu, 1903. " Ingolf " Ech., pt. I, p. 56.
East Indies ; 100-129 fathoms.
The small size, pretty colors, and very narrow ambulacra combine to
make this a very easily recognized species. The "Albatross" specimens
which are less than 50 mm. in diameter, and intermediate in size between
those figured on the " Challenger " Ech. PI. XIX, figs. 1-6, were taken at
the following station :
Station 4934. Off Kagoshima Gulf ; 30° 58' 30" N., 130° 32' E. 103-
152 fathoms. Rocky.
Three specimens.
Araeosoma eurypatum A. Ag. and CI.
Plates 66, figs. 18-19; 73-75.
As far as can be judged from the single specimen of this species, the test
must have been very flexible, the outline was lobed, the median ambulacral
and interambulacral lines bulging out beyond the vertical furrow formed at
the junction of the ambulacral and interambulacral zones (PI. 73). The
curve of the test at the ambitus is high, projecting well beyond the concave
abactinal surface of the test at the centre of which rises the abactinal system
(PI. 73, fig. 1). This is well seen in the profile view of the test (PL 73, fig. 2)
as well as in the figure taken from the actinal side (PI. 74), which also shows
the ambitus swelling well above the concave actinal surface in the centre of
which rises the highly arched, slightly conical actinal system. The test of
the specimen figured is, as far as it can be measured in its dry and some-
what folded state, 140 mm. in diameter ; the actinal system is 35 mm.
across, while the abactinal measures 20-25 mm. from the distal tip of a
genital plate to the distal edge of the opposite ocular plate (PI. 75, fig. 2).
From the ambitus to the abactinal system in the ambulacral zone there are
42 plates and in the interambulacral zone 32. On the actinal side in the
interambulacral column there are 19 plates and in the ambulacral 31. The
test of this species is remarkable for the great uniformity in the size of
the coronal plates. Those of the actinal side are but little larger than those
of the abactinal side (compare Pis. 73 and 74). The interambulacral plates
182 HAWAIIAN AND OTHER PACIFIC ECHINI.
of the abactinal side are curved downward toward the ambitus from the
outer edge of the interambulacral zone to the median line (PI. 73, fig. 1) all
the way from the abactinal system to the ambitus (PI. 75, fig. 2). The same
is the case with the ambulacral plates to a limited extent, only the plates
about one-third of the way from the ambitus towards the abactinal system
being curved towards the median ambulacral line (PI. 73, fig. 1), those nearer
the abactinal system being only slightly curved or horizontal (PL 75, fig. 2).
At the ambitus the ambulacral and interambulacral areas are of nearly
the same width (Pis. 73, 74). On the abactinal side the interambulacral
areas are bordered along the ambulacra by a more or less regular vertical
series of small primary tubercles flanked near the ambitus by a shorter
row of similar tubercles extending on five or six interambulacral plates.
The *est of the interambulacral plates are for the most part covered with
distinct small secondaries and miliaries, but along the median interambu-
lacral line are found two rows of small primaries extending from the actinal
side to the abactinal side of the ambitus. These rows are well seen in the
profile view of the test (PI. 73, fig. 2). On the abactinal surface, in the
median ambulacral area, occur two or three irregular vertical series of small
distant primaries and secondaries extending from the ambitus to the abac-
tinal system. The poriferous zones on the abactinal surface occupy two-
thirds of the ambulacral area ; the two vertical inner rows of pairs of pores
are well separated from the single outer line (PL 75, fig. 4).
On the actinal side the poriferous zones approach the outer edge of the
ambulacra and at the actinostome are closely packed (PL 75, figs. 1, 3). On
the actinal side of the test (PL 74) the interambulacral plates are of uniform
height, sharply inclined towards the median line ; only the nine or ten plates
nearest the actinostome are separated by uncalcified membrane. The verti-
cal series of interambulacral primaries next the ambulacra are regular and
prominent (PL 74), while the less marked rows of similar tubercles on each
side of the median interambulacral line are not very noticeable. The
actinal system is about 35 mm. in diameter and has prominent gill cuts.
There are twelve to fourteen rows of narrow imbricating plates between the
teeth and the ambulacral coronal plates (PI. 75, fig. i), which carry second-
aries arranged in horizontal rows.
The abactinal system (PL 75, fig. 2) is from 20 to 25 mm. in diameter.
The genital plates are pointed and much elongated with the genital open-
ings placed in the proximal part of the genital membrane, which carries
AR/EOSOMA LEPTALEUM. 183
along its edges small irregularly shaped polygonal plates. The proximal
part of the genital plate is divided into two large plates each of which carries
a small secondary. The ocular plates are polygonal, separating the genitals,
and each carries one or two secondaries.
The anal system is covered with irregular polygonal plates varying
greatly in size (PI. 75, fig. 2), with a few small elliptical plates round the
anal opening, arranged in two irregular rows.
As this species is allied to A. coriaceum, it is interesting to compare the
details of the abactinal system given on Plate 52 of the Panamic Deep Sea
Echini (Mem. M. C. Z., XXXI) with those of A. eurypatum on Plate 75 of
this Memoir.
The test is scraped so nearly bare, only a very few broken, secondary
spines, a few triphyllous pedicellarias and some scattered sphseridia are
left in a couple of abactinal folds of the test. The sphseridia (PI. 66, fig.
18) are remarkable for their greatly elongated form ; they are more spine-
like than in any other known Echinothurid. The triphyllous pedicellariae
are, as usual, on long, slender stalks ; the valves (PI. 66, fig. 19) are notice-
ably slender but expand rather abruptly at the tip, where they are very
flat ; they are about half a millimeter long and have a well-developed cover-
plate with an irregular margin.
This remarkable specimen was taken in 1888 by the "Albatross"
on her way from New York to San Francisco, at the following station :
Station 2819. Near Galapagos Islands; 6'S., 90°6'W. Bott. temp.
39.9°. 671 fathoms. Wh. s.
Araeosoma leptaleum A. Ag. and CI.
Plates 76 and 77.
This species belongs to the fenestration group of Araeosoma, and may
be considered the Pacific representative of that Atlantic species. A single
specimen was collected by the "Albatross" in 1904 off Mariato Point,
while looking up for further investigation the green-sand patch discovered
by her in the Panamic region during the cruise of 1891.
The diameter of this specimen is 125 mm. ; the greatest diameter of the
abactinal system 21 mm. ; of the actinal system, 30 mm. There are 19
plates in each half of an interambulacrum from the actinal system to the
184 HAWAIIAN AND OTHER PACIFIC ECHINI.
ambitus and 27 in the ambulacral column. Between the abactinal system
and the ambitus there are 24 plates in each half of an interambulacrum and
38 in an ambulacrum. At the ambitus the interambulacral area has a
width of 42 mm., the ambulacral, 32. The greatest diameter of the
abactinal system is 21 mm., that of the actinal system 30 mm. The
primary spines both on the actinal and abactinal surfaces are sharp and
slender, from 12 to 22 mm. in length (PI. 76). The longer spines of the
actinal side are slightly expanded at the tip (PI. 76, fig. 2), and terminate
in a small white "hoof" which is remarkable for being thickest at base
and nearly pointed at tip. Between the actinal interambulacral plates
there is even more uncalcified membrane than in A. fenestration. On the
abactinal side the calcification of the plates increases gradually from
'below the ambitus to the abactinal system (PI. 76, fig. I). Both the am-
bulacral and interambulacral plates are higher in fenestration than in
leplalenm.
On the actinal side the vertical row of interambulacral primaries border-
ing the ambulacrum is very marked, and extends just over the ambitus to
the abactinal surface, close to the ambulacral plates. On the abactinal
surface two irregular series of smaller primaries extend on each half of the
interambulacrum, two-thirds of the way to the abactinal system (PI. 76,
fi°\ 1). The two median rows of ambulacral primary tubercles are distant
and irregular (PL 77, fig. 3), but extend from the actinostome (PI. 77,
fig. l) over the ambitus (PI. 77, fig. 4) nearly to the abactinal system
(PI. 76, fig. 1). The two inner series of pairs of pores are well separated
from the outer row for nearly the whole length of the ambulacrum
(PI. 77, fig. 4), approaching closely only near the actinostome (PL 77,
fig. 3).
There are from ten to twelve rows of rather high imbricating porif-
erous plates extending from the teeth to the coronal, ambulacral plates
(PL 77, fig. 1). They each carry a horizontal row of small secondaries and
miliaries. The small area between the ambulacral plates at the proximal
margin of the primary interambulacral plate is covered with a few minute
elliptical plates. The actinal plates near the teeth all abut on each other
as regularly as the coronal plates of the typical echinoid test; it is only
the plates near the coronal plates which are imbricating. The median
suture of the interambulacral area extends almost unbroken from the
actinal edge of the test to the teeth, and the adjoining ambulacral areas
ARiEOSOMA LEPTALEUM. 185
are separated only near the corona by the small irregular wedge-shaped
interambulacral plates. Such an arrangement is suggestive of Bothrio-
cidaris, where the interambulacral area is reduced to a minimum.
The abactinal system is comparatively small (PI. 77, fig. 2). The
genital plates are pointed triangular with rounded angles, while the genital
membranes are elongated and more or less rectangular. The genital plate is
made up of two parts, a small outer piece distal to the membrane and a
broadly horse-shoe-shaped plate proximally, which carries from one to three
small secondaries or miliaries. The madreporic body is transverse elongate
with slightly concave sides. The anal system is covered with two outer
rows of larger polygonal plates, each carrying one or two secondaries or
miliaries and two or three interior series of small elliptical and polygonal
plates adjacent to the anus.
The pedicellariae of this species are remarkably indistinctive, and it has
not seemed necessary to figure them. No dactylous pedicellariae were found.
The tridentate pedicellariae are not very abundant and show comparatively
little diversity of size. Most of them have the heads about a millimeter
long and the stalk three or four times that length. The shape of the head
and valves is much like what we find in thetidis (see PI. 66, fig. 17), but
some pedicellariae are much more like those of Sperosoma (see PL 64,
fig. 9). Occasionally one is met with which approaches fig. 12, PI. 67, and
the valves are often broadened distally and narrowed near the base, like
fig. 13, PI. 67.
The triphyllous pedicellariae are more common, though hardly abundant.
The necks and stalks are very long and slender ; the valves are very much
like that shown in fig. 19, PI. 66, but are not quite so flattened or abruptly
widened at the tip.
The sphceridia are very long and club-shaped, reminding one very much
of those of the previous species (eurypatiim).
The single specimen of this interesting species was taken by the
" Albatross " at the following station :
Station 4621. Off Mariato Point, Panama; 6°36'N., 81°44'W. 581
fathoms ; modern green-sand ; temperature of bottom not recorded, but
adjoining this station, 40.2° was recorded in 555 fathoms, in 1891.
186 HAWAIIAN AND OTHER PACIFIC ECHINI.
Araeosoma hystrix A. Ag. and CI.
Calveria hystrix Carpenter and Jeffreys, 1871. Proc. Roy. Soc. London, XIX, p. 154.
Calveria hystrix Wyv. Thomson, 1872. Proc. Roy. Soc. London, XX, p. 494.
(Not Calveria hystrix Carpenter, Jeffreys and Thomson, 1870, Proc. Roy. Soc. London, XVIII, p. 445.)
Asthenosoma hystrix A. Agassiz, 1872. Rev. Ech. Pt. I, p. 93.
North Atlantic ; 100-1000 fathoms.
In confirming Agassiz's rejection of Calveria (Pan. Deep-Sea Ech., p. 84),
Bather has pointed out (Ann. Mag. Nat. Hist. (7) XVII, p. 249) that the <
specific name (hystrix) having heen rejected as a homonym, it should not be
used for this species. This may be correct nomenclature, but we cannot see
what is gained by any change from the universally used specific name.
Araeosoma pyrochloa A. Ag. and CI.
Asthenosoma pyrochloa A. Agassiz and Clark, 1907. Bull. M. C. Z., LI. p. 118.
Plates 66, figs. 1-k; 78-80.
Although this species bears a close resemblance to the preceding, the
differences pointed out on p. 175 seem to be constant, and warrant the rec-
ognition of this form as the North Pacific representative of A. hystrix,. The
small size of the actinostome is particularly worthy of note. The diameter
of the specimen figured on Plates 78 and 79 is 196 mm. From the ambitus
to the abactinal system there are in each column 35 interambulacral plates,
each carrying from one to four primary tubercles arranged in four or five
irregular vertical rows. On the actinal side of the test there are 25 plates in
each half-interambulacrum, and each plate carries two to four primary tuber-
cles, one of which is always at the extreme ambulacral end of the plate. A
very complete marginal series is thus formed, but the series near the median
line is much less regular. The rest of the interambulacral plates are covered
with numerous secondaries and miliaries. The plates increase in height
somewhat as they pass from the ambitus towards the abactinal system and
actinostome. On the abactinal side of the test (PI. 78) there are in each
column 48 ambulacral plates, increasing very gradually in height from the
ambitus to the abactinal system. Each plate carries one or two primary
tubercles, which form two very irregular vertical rows on each half-
ambulacrum. Excepting the extreme outer end, the ambulacral plates are
covered with a series of large miliaries. Towards the ambitus, on the
abactinal side of the test, the poriferous zone is equal in width to half that
AB/EOSOMA PYEOCHLOA. 1S7
of the ambulacral plates. At the ambitus the width of the ambulacra!
area is 50 mm., and that of the inter ambulacral 73 mm. There is a narrow
bare space running between the ambulacral and the interambulacral areas,
and a somewhat wider bare space on the median interambulacral line. On
the actinal side there are 34 plates in each half-ambulacrum. These plates
carry two principal vertical rows of primary tubercles (PI. 79) ; one row of
small tubercles extends from the actinostome above the ambitus in the space
separating the single series of pores from the double column, and one row
of large tubercles runs along the median ambulacral line. The latter
is flanked with an irregular row of smaller primaries extending about half
way from the ambitus to the actinal system. The rest of the ambulacral
plates carry small secondaries and miliaries irregularly arranged, as on the
interambulacral plates.
The uncalcified membrane between the interambulacral plates has its
greatest width about half way between the ambitus and the actinal system.
On the abactinal side of the test (PI. 79) the bare space separating the
coronal plates is reduced to a narrow line (PL 80, fig. £).
On the actinal side of the test many of the larger primary spines are
somewhat flaring at the extremity ; the others are straight and sharp, as are
the miliary and secondary spines. On the abactinal side of the test the
primary spines are sharp, slender, and straight, very slightly tapering. The
miliary and secondary spines are slender and fine ; those of the abactinal
part of the test are longer than the others, especially in the interambu-
lacral area.
The greatest diameter of the abactinal system is 26 mm. (PI. 80, fig. 2).
The genital plates are comparatively small, very pointed, with a broad plate
adjoining the anal system and smaller plates adjoining the genital mem-
branes. The larger plates carry from five to seven secondaries, with a few
miliaries irregularly arranged ; the other plates carry large or small miliaries
according to their size.
The oculars are large, irregularly heptagonal (PI. 80, fig. 2), carrying,
next to the anal system, from seven to ten medium-sized secondaries with a
few miliaries. The ocular pore is very small. The anal system is covered
by three or four unevenly concentric rows of irregularly shaped polygonal
plates, carrying small secondaries like those of the genital and ocular plates,
and occasionally a few small miliaries, with an inner belt of very small
elliptical plates round the anal opening.
188 HAWAIIAN AND OTHER PACIFIC ECHINI.
The madreporic body is divided into two plates, the larger being rectangu-
larly elongated transversely, forming the proximal base of the genital plate ;
the smaller is pentagonal and adjoins the odd anterior ocular plate.
The actinal system measures 32 mm. in greatest diameter. It is covered
with twelve or thirteen rows of imbricating concentric ambulacral plates,
each carrying a horizontal row of small secondaries (PI. 80, fig. 1). The
plates do not extend quite to the teeth, and diminish rapidly in size from the
base of the corona where they overlap sideways and vertically. A wide,
bare, triangular space is thus left between each set of ambulacral plates
(PI. 80, fig. 1) next the teeth, much as in A. thetidis, but not quite as
marked as in that species (PI. 70, fig. 2).
The pedicellarice of pyrochloa are so nearly like those of liystrix that no
extended description is necessary. The large tridentate (PI. 66, fig. 1) have
the valves .80-1.75 mm. long, while in the small tridentate (fig. 2) they are
only .70-85 mm. in length. The triphyllous pedicellarice (PL 66, fig. 3) are
very small, on very slender stalks ; the valves measure only .30-40 mm. in
length. The sphccridia are somewhat club-shaped, .50-60 mm. long. The
calcareous spicules in the tube-feet are very numerous perforated plates of
irregular form and size ; some are nearly half a millimeter in diameter, and
have about a hundred perforations.
This species was taken by the " Albatross " at the following stations, the
specimens ranging from 100 to 195 mm. in diameter:
Station 4919. Off Kagoshima Gulf, Japan ; 30° 34' N., 129° 19' 30" E.
Bott. temp. 41.8°. 440 fathoms. Glob. oz.
Station 5086. Off Joka Sima Light, Japan; 35° 8' 15" N., 139° 20' E.
Bott. temp. 43.7°. 292 fathoms. Gn. m., crs. bk. s.
Three specimens.
Araeosoma Belli Mortens.
Asthenoaoma hyatrix A. Agassiz, 1874. " Hassler " Ech., Mem. M. C. Z., IV, p. 3; PI.
II, figs. 1, 2. 1880. Bull. M. C. Z., VIII, p. 74.
Araeoaoma BeUl Mortensen, 1903. " Ingolf " Ech., I, p. 55.
Caribbean Sea; 103-140 fatjjoins.
Plate 66, fig. 5.
Although Mortensen's species is based on the characters shown by the
pedicellariae, we find that the peculiarities of the test, pointed out in 1874,
AR^EOSOMA BELLI. 189
justify the recognition of this small West Indian species. The largest
specimen before us is only 105 mm. in diameter.
This species is readily distinguished from A. hjstrix by the greater
height of both the ambulacral and interambulacral plates. In a specimen
of A. Belli 72 mm. in diameter there are 22 interambulacral and 27 am-
bulacral plates in each column, from the ambitus to the abactinal system.
On the actinal side, 16 interambulacral and 17 ambulacral plates in a
column lie between the ambitus and the actinal system.
In a specimen of the same species 105 mm. in diameter there are 27
interambulacral and 40 ambulacral plates between the ambitus to the
abactinal system. On this actinal side there are, from the ambitus to
the actinal system, 18 interambulacral and 18 ambulacral plates.
In a specimen of A. hystrix 130 mm. in diameter we find on the abactinal
side 27 interambulacral and 38 ambulacral plates between the abactinal
system and the ambitus, and on the actinal side between the actinal system
and the ambitus there are 22 interambulacral and 33 ambulacral plates.
In A. Belli there are two principal columns of interambulacral pri-
maries on the actinal side, one of which includes a primary on each plate
adjoining the ambulacral system ; the other is nearer the median line, and
includes only one on every other plate. These columns extend but little
beyond the ambitus (" Hassler" Ech., PL II, figs. 1, 2); a secondary column
of distant and irregularly placed primaries extends from the ambitus to the
abactinal system. The ambulacral and interambulacral plates each carry
one irregular row of small secondaries and miliaries at the centre of the
plate.
In A. hystrix there are on the interambulacral plates six or seven
vertical rows of primaries and secondaries, four of which are more prominent
and regular than the others. In the median ambulacral area there are
two series of primary tubercles. The rest of the plates, in both areas, are
thickly covered with miliaries and a few very small secondaries.
The arrangement of the primaries and secondaries is much the same on
the abactinal side, with the exception that the primary tubercles are
smaller.
There are, both in A. Belli and A. hystrix, on the actinal side, spines
with hoofs and many with a flaring extremity.
190 HAWAIIAN AND OTHER PACIFIC ECHINI.
Araeosdma violaceum Mortens.
Araeosoma violaceum Mortensen, 1903. "Ingolf" Ech., I, p. 176.
West of Ireland ; 199 fathoms.
We know nothing further of this species than what is given in the
original brief description.
Araeosoma coriaceum Mortens.
Asthenosoma coriaceum A. Agassiz, 1879. Proe. Am. Acad., XIV, p. 201. 1881.
" Challenger " Ech., PL XVIIa, figs. 5-7. 1904. Pan. Deep Sea Ech., p. 115, PI. 52.
Araeosoma coriaceum Mortensen, 1903. "Ingolf" Ech., I, p. 53.
Vicinity of Tonga and Fiji Islands; 240-310 fathoms.
The large size, dark brown color, and very leathery test are noticeable
features of this species.
Araeosoma tessellatum Mortens.
Asthenosoma tessellatum A. Agassiz, 1879. Proc. Am. Acad., XIV, p. 201. 1881.
"Challenger" Ech., Pis. XlXa, fig. 1; XlXb. (Not A. tessellatum A. Ag. and CI.,
1907. Bull. M. C. Z., LI, p. 117.)
Araeosoma tessellatum Mortensen, 1903. " Ingolf" Ech., I, p. 54.
Philippine Islands; 100-115 fathoms. Kei Islands; 168 fathoms.
We are unable to add anything further to the facts known about this
species.
Araeosoma fenestratum Mortens.
Calveria fenestrata Wyville Thomson, 1872. Proc. Roy. Soc. London, XX, p. 494. 1874.
Phil. Trans. Roy. Soc. London, 164, pt. 2, Pis. LXIII, figs. 9, 10; LXVI, LXVII.
Asthenosoma fenestratum A. Agassiz, 1881. "Challenger" Ech., p. 210.
Araeosoma fenestratum Mortensen, 1903. " Ingolf" Ech., I, p. 52.
Asthenosoma Reynoldsii A. Agassiz, 1S80. Bull. M. C. Z., VIII, p. 75.
Asthenosoma hystrts A. Agassiz, 1883. "Blake" Ech., Pis. XIII, XIV.
North Atlantic Ocean ; 81-373 fathoms.
PI. 66, fig. 20.
While we do not feel sure that the Caribbean species {Reynoldsii) is
identical with Wyville Thomson's fenestratum, as we have had no European
specimens for comparison, it seems to be true, as Mortensen has pointed
out, that both are distinct from hjstrix. It is worthy of note that in the
Caribbean specimens the dactylous pedicellariae, which may be entirely
wanting in otherwise normal specimens, not rarely have five valves (PI. 66,
fig. 20). The very large tridentate pedicellariae are sometimes wanting.
AK^EOSOMA GRACILE. 101
Arseosoma gracile A. Ag. and CI.
Asthenosoma gracile A. Agassiz, 1881. " Challenger " Ecli., p. 89; PI. XVIIa, figs. 1-4.
Asthenosoma longispinum Yoshiwara, 1897. Ann. Zool. Japon., I, p. 5.
Calveria gracilis Mortensen, 1903. " Ingolf " Ech., I, p. 51.
Asthenosoma tessellatum A. Ag. and CI., 1907. Bull. M. C. Z., LI, p. 117. (Not A. tessel-
latum A. Ag. " Challenger " Ech., p. 88.)
Off Japan and the Philippines ; 50-255 fathoms.
Plates 81, figs. 3, 4; 82, figs. 5-8.
On drying the specimen and making a more careful examination of it,
we find that we were mistaken in referring to A. tessellatum an Echinothurid
taken by the "Albatross" in 1906. The specimen is badly damaged, and
the uniform dark brown color like that of tessellatum misled us. In spite of
the peculiar color, it seems best to us now to refer the specimen to A.
gracile, the structure of the test and the pedicellarios agreeing well with that
species. But there can be little doubt that gracile and pyrocliloa are very
near each other and both are very near hystrvc, and the differences of color
are as important as any that have been pointed out. But if we make
color the criterion, the specimen before us cannot belong to any of the
three species mentioned.
We refer to gracile with some hesitation, the small specimen from Station
3750, shown on Plate 81 (figs. 3-4). The arrangement of the actinal tube-
feet shows clearly that it is an AraBosoma, while comparison with young
specimens of Owstoni, the commonest Japanese form of that genus, shows it
cannot belong to that species. The coronal plates are much more numerous
than in Owstoni at the same age, and the tuberculation of the test is different,
the abactinal interambulacral plates being quite bare (PI. 81, fig. 4). As
the large pedicellarias are like those of gracile and pyrocliloa, we believe it
belongs to one of those species (though the color is quite bleached), and the
depth at which it was taken certainly indicates gracile.
The specimens, which are 30 and 140 mm. in diameter respectively, were
taken by the "Albatross" at the following stations:
Station 3750. Off Suno Saki, Honshu Island, Japan. 83-140 fathoms.1
Gy. s., brk., sh.. p.
Station 4943. Kagoshima Gulf, Japan ; 31° 24' 35" N., 130° 38' 40"
E. 119 fathoms. Character and temperature of bottom not recorded.
1 The label with the specimen gives the depth as S3-89 fathoms.
192 HAWAIIAN AND OTHER PACIFIC ECHINI.
ArseOSOma Owstoni Mortens.
Araeosoma Owstoni Mortensen, 1904. Ann. Mag. Nat. Hist. (7) XIV, p. 82 ; Pis. II and
V, figs. 4-9, 11, 18-20.
Asthenosoma Owstoni A. Agassiz and Clark, 1907. Bull. M. C. Z. LI, p. 117.
Sagami Bay, Japan ; 50 fathoms.
Plates 81, figs. 1, 2, 5, 6 ; 82, figs. 1-t.
The specimens before us show considerable diversity of color, but it
is difficult to say how much of this is due to preservation. The small
individuals are very pale, almost white. Some medium-sized specimens are
decidedly reddish ; one is nearly brick red. The larger specimens are dull
pale purplish. In most of the specimens the actinal spines are decidedly
pinkish, while those of the abactinal side are greenish or not colored. The
pedicellariae agree with Mortensen's description and figures. Young speci-
mens of A. Oivstoni measuring 53 mm. and 21 mm. in diameter (Pis. 81,
figs. 1, 2, 5, 6; 82, figs. 1-4.) are characterized by the proportionally wider
ambulacral area as compared to the interambulacral one. In the specimen
measuring 53 mm. in diameter (PI. 81, fig. 2) the actinal primary inter-
ambulacral spines already carry a hoof. In the smaller specimen all the
actinal primary spines are broken or missing. The hoofs are very numer-
ous and very large on the primary actinal interambulacral spines of large
specimens (150 mm. in diameter).
In the younger specimen (21 mm.) the two principal vertical rows of
interambulacral primaries are largest near the apical system (PI. 81, fig. 5),
but in the older one (PI. 81, fig. l) they already have all the characters of
the larger and full-grown specimens, both on the actinal and abactinal side
of the test. In the specimen of 52 mm. the primary abactinal interam-
bulacral spines are proportionally more slender and longer than in larger
specimens (150 mm. in diameter) in which they are relatively stout.
The actinal system of the 52 mm. specimen (PI. 82, fig. i) is covered with
four and five horizontal rows of ambulacral plates, and close to the inter-
ambulacra there are a few minute elliptical plates. The ambulacral plates
carry a small secondary at the extremity of each plate and occasionally a
small miliary. At this stage (PI. 81, fig. l) the genitals and oculars are of
nearly the same size, the genitals separating the oculars (PI. 82, fig. 2). The
oculars, as in the young of many other species of Araeosoma, extend outward
between the two upper plates of the adjoining interambulacral areas. The
AR,EOSOMA OWSTONI. 193
genitals and oculars each carry a small secondary, with one or two miliaries
in the central part of the proximal margin of the plate. The anal system is
covered with three or four irregular concentric rows of polygonal plates, a
few of the larger of which each carry a small secondary.
In the small specimen, measuring 21 mm. in diameter (PI. 81, figs. 4, 5),
there are from the ambitus to the abactinal system 9 interambulacral and 15
ambulacral plates, in each column, while between the ambitus and the
actinal system there are 7 interambulacral and 12 ambulacral plates.
In the specimen measuring 52 mm. in diameter (PI. 81, figs. 1, 2) there
are 14 interambulacral and 23 ambulacral plates, from the ambitus
to the abactinal system. On the actinal side there are 11 interambu-
lacral and 14 ambulacral plates from the ambitus to the actinal system.
In a large specimen measuring 150 mm. in diameter, from the ambitus to
the actinal system there are 17 interambulacral and 27 ambulacral plates,
and between the ambitus and the abactinal system, 25 interambulacral and
47 ambulacral plates. The plates of the ambulacral areas are thus seen to
increase in number much more rapidly than the interambulacral plates.
The specimens, which range from 20 to 150 mm. in diameter, were
taken by the " Albatross " at the following stations :
Station 4875. Eastern channel, Korea Strait; 34° 19' N., 130° 9' E.
59 fathoms. Fne. gy. s., brk. sh.
Station 4876. Eastern channel, Korea Strait ; 34° 20' N., 130° 10' E.
Bott. temp. 62.1°. 59 fathoms. Fne. gy. s., brk. sh.
Station 4877. Eastern channel, Korea Strait; 34° 20' 30" N., 130°
11' E. 59 fathoms. Fne. gy. s., brk. sh.
Station 4880. Eastern channel, Korea Strait; 34° 16' N., 130° 16' E.
59 fathoms. Fne. gy. s., brk. sh.
Station 4946. Between Kagoshima and Kobe, Japan ; 31° 29' 10" N.,
130° 34' 30" E. Bott. temp. 68.7°. 39 fathoms. Br. s., brk. sh., p.
Station 5095. In Uraga Strait, Gulf of Tokyo, Japan ; 35° 5' 34" N.,
139° 38' 36" E. Bott. temp. 57.8°. 58 fathoms. Fne. bl.,s., brk. sh.
Bathymetrical range, 39-59 fathoms. Extremes of temperature, 68.7°-
57.8°.
Eleven specimens.
13
194 HAWAIIAN AND OTHER PACIFIC ECHINI.
Sperosoma.
Kcehler, 1897. Zool. Anz. XX, p. 302.
Type-species, Sperosoma Grimaldii Kcehler, 1. c.
The general appearance of Sperosoma is much like that of Echinosoma,
the test being, as in that genus, thin and flexible with little difference
between the upper and lower sides. The spines and tubercles of the
actinal side are larger than those above and the primaries have well-
developed hoofs. The actinal tube-feet are in three distinct series and
have small sucking-discs or none. The splueridia are as in Echinosoma.
Although the characteristic actinal ambulacra are very remarkable and
serve well to distinguish the genus, it must not be supposed that the separa-
tion of the primary ambulacral plate into an outer poriferous and an inner
non-poriferous part is a feature confined to Sperosoma. Many specimens of
Echinosoma tenue (and doubtless other members of that genus) show the
same phenomenon to a greater or less degree. It is quite common in
team to find the inner and outer halves of the primary plate separated by
a suture, even though narrowly in contact, and occasionally the two sec-
ondary elements nearly, if not quite, meet between them. This formation
of plates by resorption is one of the characters in which the Echinothuridoe
are most unique. The essential difference between Sperosoma and Echi-
nosoma in the structure of the ambulacrum is in the position of its component
parts ; thus although the primary plate of Echinosoma may be divided into
two parts, there are not four columns of plates in each half-ambulacrum,
for the upper (outer) secondary element lies above the outer half of the
primary plate and is more or less extensively a part of the interambulacral
margin of the ambulacrum. In Sperosoma, the outer halves of the primary
plates lie one above the other, broadly in contact, and forming the outer
of the four half-ambulacral columns. In Echinosoma this is not the case,
the outer column consisting of outer halves of primaries alternating with
the upper secondary plate elements, more or less irregularly. The existence
of a pair of median columns of imperforate ambulacral plates is a feature
in which Sperosoma is absolutely unique among all recent regular Echini,
but when we recognize the origin of the plates which compose them, we
see that it is not so much their presence, as the way in which they are
formed, that is really remarkable. In well-preserved specimens one can
SPEROSOMA. 195
trace (as Mortensen ("Ingolf" Ech. II, p. 171, fig. 27) has done in a very
young specimen) the development of the ambulacral plates from their
origin next the ocular plate, where we find a primary with a secondary
element above and another below it, the three of nearly equal size ; through
the stage where the primary is much the largest and much wider than high,
while the upper secondary has taken an outer, the lower an inner position ;
through another stage where the secondary elements have so encroached
on the primary that the outer and inner halves are only narrowly connected,
the pore-pair being in the outer half ; to the full four-column arrangement
of the actinal side, where the plates are more or less nearly of a size
and the distinction between primary and secondary elements is almost
obliterated.
Mortensen (1903, "Ingolf" Ech., I, p. 63) says of Sperosoma that
sucking-discs are well developed on the feet. We judge this is a slip of
the pen, for observation on many specimens indicates that they are wanting,
or rudimentary, as shown in his PI. XIV, fig. 4-
There seem to be six recognizable species in this genus, which may be
distinguished as follows :
'ol
Abactinal ambulacral plates not twice as numerous as actinal.
Primary spines of abactinal surface numerous, 150-500 or more in
specimens over 100 mm. h. d.
Abactinal tube-feet few in an imperfect double series ; poriferous
zone very narrow ; actinal primary spines rather less than
150 Grimaldii.
Abactinal tube-feet more numerous in three unequal series, a
more or less distinct quincunx arrangement being evident;
poriferous zones often quite broad; actinal primary spines
rather more than 150 quincunciale.
Primary spines of abactinal surface few, never exceeding 125 and
usually fewer than 75, sometimes nearly or quite wanting.
Abactinal primary tubercles very small or wanting; ambulacra
much wider than interambulacra giganteum.
Abactinal primary tubercles large, with areolae often occupying
whole height of plate ; ambulacra about as wide as inter-
ambulacra obscurum.
Abactinal ambulacral plates more than twice as numerous as actinal.
Abactinal tube-feet in two distinct series ; no ambulacral plates
extending across an entire half-ambulacrum biseriatum.
Abactinal tube-feet in a single crowded series ; some ambulacral
plates extend across the entire half-ambulacrum durum.
196 HAWAIIAN AND OTHER PACIFIC ECHINI.
Sperosoma Grimaldii Koehler.
Sperosoma Grimaldii Koehler, 1897. Zool. Anz., XX, p. 302. 1898, " Hirondelle" Ech.,
Pis. II, III, etc.
North Atlantic ; 165-930 fathoms.
In addition to one of the " Thor " specimens, received in exchange from
the Copenhagen Museum, there lies before us a specimen of Sperosoma
taken by the " Blake " off Barbados in 399 fathoms. This specimen is
only 110 mm. in diameter, but the structure of the actinal ambulacra is
the same as in large specimens. The color is reddish purple. This speci-
men had been identified as " Phonnosoma Petersii," no part of an actinal
ambulacrum having been cleaned for examination of the plates, and the
general facies being very much like Petersii. Its pedicellariae are all rather
small and agree well with Mortensen's figures of those of Grimaldii. The
" Thor " specimen has some very large pedicellariae, but they are widely
scattered ; the smaller ones are rather different in form from the published
figures, the base of the valves being somewhat swollen.
Sperosoma quincunciale de Meij.
SperoBoma quincunciale de Meijere, 1904. " Siboga " Ech., p. 40 ; PI, XIII. figs. 166-176.
South of Timor ; 490 fathoms.
The specimens before us, except for some diversity in color and in the
arrangement of the feet abactinally, agree well with de Meijere's description.
While the general coloration is distinctly violet of some shade, two or
three of the specimens have the abactinal surface and the actinal spines
quite yellow. None of the specimens are as large as de Meijere's type.
They range from 140 to 170 mm. in diameter. In most of the specimens
the tube-feet show the quincunx arrangement abactinally quite plainly,
but in one or two specimens the foot on the upper secondary plate-ele-
ment, instead of being on the same level as that of the lower secondary
element of the plate above, is decidedly below it, and the quincunx arrange-
ment, is thereby obscured, the first impression being that of a zigzag line of
feet. In other respects these specimens are normal, and we see no reason
to consider this peculiarity other than individual variation. The actinal
primary spines are provided with large and conspicuous white " hoofs."
Many of the actinal primary spines of these Japanese specimens are in-
fested with a parasitic copepod, apparently identical with Echinocheres globosus
SPEROSOMA GIGANTEUM. 197
Hansen, which Mortensen found in the spines of Arceosoma gracile. They
produce a swelling in the shaft of the spine, with a small opening at the
distal end, giving water access to the cavity in which the animal lives. Not
rarely there are two of those parasites in the shaft of a single spine.
The " Albatross " took the species at the following stations :
Station 4957. Between Kagoshima and Kobe, Japan ; 32° 36' N., 132°
23' E. Bott. temp. 39.8°. 437 fathoms. Gn.-bn. m., fine. gy. s., for.
Station 5079. Off Omai Saki, Japan; 34° 15' N., 138° E. Bott. temp.
39.1°. 475-505 fathoms. P.
Station 5080. Off Omai Saki, Japan ; 34° 10' 30" N., 138° 40' E. Bott.
temp. 38.7°. 505 fathoms. Fne. gy. s., glob.
Bathymetrical range, 437-505 fathoms. Extremes of temperature,
39.8°-38.7°.
Seven specimens.
Sperosoma giganteum. A. Ag. and CI.
Sperosoma giganteum. A. Agassiz and Clark, 1907. Bull. M. C. Z., LI, p. 120.
PI. 64, figs. 9-12 ; 65, figs. 2-5 ; 83-86.
This remarkable sea urchin measures nearly 320 mm. in its greatest di-
ameter. The color is deep purple, almost black. The ambulacral area is
extraordinarily wide, for on the abactinal surface just above the ambitus it
measures over 110 mm., while the interambulacrum is a little over 80 mm.
(PI. 83). The outer and inner columns in each half of each ambulacrum are
made up of remarkably long low plates, which just above the ambitus are 25
mm. long and only 5 mm. high (Pis. 83, 86, fig. 2). There are no primary
tubercles above the ambitus, but the whole abactinal surface is rather
closely covered with slender secondaries and miliaries (PI. 83). On the
actinal surface (Pis. 84, 86, fig. 1) primary spines are fairly numerous but
irregularly placed, showing no regular arrangement. Many ambulacral
plates have two, and many interambulacral plates four, spines. The areolae
are small (PI. 86, fig. 1), the diameter usually less than half the height of
the plate. The primary spines of the actinal surface are nearly all broken
off ; the remaining ones are seldom 25 mm. long, and terminate in a
conspicuous white hoof (PI. 84).
Both the actinal and abactinal systems of this species (PI. 85, figs. 2, 1)
differ greatly from the figures given by Koehler of S. G-rimaldii, as well as
198 HAWAIIAN AND OTHEE FACIFIC ECHINI.
those by Doderlein of S. hiseriatmn and those here given of S. obscurum
(PI. 89).
The actinal system of S. Grimaldii as figured by Kcehler shows its
plates to be closely packed with small secondaries arranged horizontally
completely connecting the sutures ; nor does Koehler figure any actino-
stomal ambulacral pores. The actinostomal ambulacral plates of S.
giganteum (PI. 85, fig. 2) are, on the contrary, well separated, arranged in
ten vertical series.
In all the other species of Sperosoma, of which the abactinal system has
been figured, the genital and ocular plates are most distinct, and while each
genital is made up of many plates, it is a simple matter to distinguish them
from the anal plates. However, such is not the case in S. giganteum, for it
seems impossible in the maze of polygonal anal plates, with their close
granulation (PI. 85, fig. 1) encroaching upon the broken genital and ocular
plates, to distinguish the limits of the latter. It is of course possible that
this great breaking up of the plates of the abactinal system may be due to
age. The madreporic plate is irregularly circular, surrounded with small
plates and edged with miliaries. It is the only genital one can trace with
any certainty (PL 85, fig. 1), and of the oculars, the left posterior is the only
one at all distinct.
The pedicellarioe are interesting, for in addition to tridentate pedicel-
larise similar to those of S. biseriatum Dod. (but seldom with valves as
much as two millimeters long) we find ophicephalous and triphyllous
pedicellariae abundant. The latter are not peculiar, but the former are
almost exactly like those figured by Mortensen (1903, PI. 14, fig. 23) as
characteristic of his proposed new genus " Tromikosoma " ! In no other
respect, however, does this species resemble that group. All the pedi-
cellariae are numerous but small. The tridentate and triphyllous occur
practically everywhere, but the ophicephalous seem to be confined to the
ambital region.
The tridentate (PI. 64, fig. 9) are provided with comparatively short stalks
and have a very short neck ; the stalks slightly exceed the head in large
examples, but are three or four times the head in small ones. The valves
(PI. 64, figs. 10-11) range from .40 to 1.20 mm., but are most commonly less
than a millimeter. They are blunt, often decidedly rounded at tip, and the
margins are very slightly sinuate, or a little concave at the base of the blade.
In large examples there is more or less of a calcareous mesh-work in the blade.
SPEROSOMA OBSCURUM. 199
The triphyllous pedicellarioe are not peculiar, save that the valves (PI.
64, fig. 12) are rather wide, with a fairly well developed and apparently
imperforate cover-plate ; they measure about half a millimeter in length and
more than half that in width at the tip.
The ophicephalous pedicellarise (PI. 65, figs. 1, 2) are very common on the
abactinal surface, just above the ambitus, but become less common as we
pass toward either pole, and are practically wanting at a distance of 75
mm. from the ambitus. The stalks are three or four times as long as the
heads. The valves (PI. 65, fig. 3) are .60-. 70 mm. in length and have the
form usual in the Echinothuridae.
The sphseridia and calcareous spicules (perforated plates) in the tube-feet
show no noteworthy features.
The single specimen of this species was taken by the " Albatross " at
the following station :
Station 5082. Off Omai Saki Light, Honshu Island, Japan ; 34° 5' N.,
137° 59' E. Bott. temp. 37.7°. 662 fathoms. Gn. m., fne. s., glob.
Sperosoma obscurum A. Ag. and ci.
Sperosoma obscurum A. Agassiz and Clark, 1907. Bull. M. C. Z., L., p. 239.
Plates 62, fig. 4; 63, fig. l; 65, figs. 4-U; 87-89.
A large number of specimens of Sperosoma were collected among the
Hawaiian Islands, which could not be referred to any previously known
species of the genus. In a specimen measuring 169 mm. in diameter there
are 19 interambulacral plates (PI. 87) between the ambitus and the abactinal
system in each column, and 25 ambulacral plates. At the ambitus the
interambulacral area measures 55 mm. across and the ambulacral 50. On
the abactinal surface there are comparatively few primary tubercles, forming
irregular vertical rows on each side of the interambulacral area. They
have large scrobicular circles (PI. 87), and carry comparatively stout
spines. The rest of the abactinal surface of the test is covered with distant
small, sharp, and slender secondary and miliary spines (PI. 89, fig. 4).
On the actinal side there are 18 ambulacral and 13 interambulacral
plates between the actinal system and the ambitus. Each of the central
ambulacral plates near the ambitus carries one large primary tubercle (Pis.
88, 89, fig. 8), and in the interambulacral area (Pis. 88, 89, fig. 4) there is
one at each extremity of the plate.
200 HAWAIIAN AND OTHER PACIFIC ECHINI.
The pores on the abactinal surface are arranged in a double series on
each side of the ambulacrum, but the outer series contains fifty per cent
more pores than the inner, and a quincunx arrangement is seldom visible
(PI. 89, fig. 4). The greater part of the actinal surface, especially about
the actinostome, is closely covered with small tubercles of more or less
uniform size (Pis. 88, 89, fig. 1), giving an appearance not wholly unlike
Chcetodiadema ; this is most marked in large individuals.
The actinal system (PI. 89, fig. l) is well covered by about eight con-
centric series of narrow plates, each carrying one row of small secondaries ;
the plates decrease rapidly in size adorally and leave small bare areas
between the adjoining ambulacra close to the mouth.
-In the abactinal system (PL 89, fig. 2) the ocular plates are compara-
tively small, with distinct pores, and each carries two or three miliaries or
secondaries. In the specimen figured three of the genital plates are well
limited, and each carries from two to six small secondaries and miliaries.
With the other genitals, one cannot separate the plates of the anal system
from those which may be small proximal parts of the genital plates. The
genital pore is about in the centre of an elongate rectangular membrane
extending well down between the columns of abactinal interambulacral
plates. There are three to five rows of irregularly shaped small anal
plates, each carrying one or two small secondaries or miliaries.
The coloration of this species is rather variable, for while most of the
specimens are more or less decidedly violet or purple, some large ones are
distinctly gray or yellowish-brown ; the plates, at least abactinally, are
frequently quite plainly outlined in a shade darker than the rest of the
test.
The pedicellariae are abundant and rather characteristic. No ophicepha-
lous pedicellariae were found. The tridentate pedicellariae (PI. 65, figs. 4, 5)
occur everywhere and in very diverse sizes. The stalks (PI. 65, fig. 7) are
usually twice the length of the head, and may be three or four times as
long. The valves (PI. 65, figs. 6, 9, 10) are slender, often very slender,
compressed, in contact distally, and usually well separated at the base ;
the lateral margin is broadly curved where the blade joins the base
(fig. 10) ; much more rarely the blades are in contact for most of their
length, and the lateral margins are abruptly curved in (fig. 9) where the
blade joins the base. The valves range in length from half a millimeter
to nearly three millimeters.
SPEROSOMA OBSCURUM. 201
The triphyllous pedicellariae are abundant everywhere. The necks are
long and slender, often three times as long as the head, and the stalks
(PI. 65, fig. 8) may be twice as long as the neck or even longer. The
valves (PI. 65, figs. 11, 12) are somewhat variable in form and proportions ;
they are one-third to one-half a millimeter in length, and the tip may be
rather abruptly truncate, and in width considerably more than half the
length, or it may be more rounded and in width less than half the length.
The cover-plate is perforated but is only slightly developed.
The sphceridia (PL 65, fig. 13) are rather large and occur well up on to
the abactinal side. The calcareous plates (PI. 65, fig. 14) in the tube-feet
are rather small but fairly abundant.
This species was taken by the " Albatross " at the following stations,
the specimens ranging from 20 to 220 mm. in diameter :
Station 3824. Off Lae-o Ka Laau Light, Molokai, Hawaiian Islands.
Bott. temp. 49.5°. 222-498 fathoms. Co., r., brk. sh.
Station 3865. Between Maui and Molokai, H. I. Bott. temp. 44.8°-
45°. 256-283 fathoms. Fne. vol. s., r.
Station 3979. Off Modu Manu, H. I. Bott. temp. 54°. 222-387
fathoms. Fne. wh. s., for., r.
Station 3988. Off Hanamaulu, Kauai, H. I. Bott. temp. 40°. 165-
469 fathoms. Gy. for., s., p.
Station 4015. Off Hanamaulu, Kauai, H. I. Bott. temp. 41.2°. 318-
362 fathoms. Gy. s., r.
Station 4021. Off Hanamaulu, Kauai, H. I. Bott. temp. 44°. 286-
399 fathoms. Co. s., for.
Station 4025. Off Mokuaeae Point, Kauai, H. I. Bott. temp. 44.9°.
275-368 fathoms. Fne. gy. s., brk. sh., for.
Station 4036. Off Kawaihae Light, Hawaii, H. I. Bott. temp. 38.2°.
687-692 fathoms. Fne. dk. gy. s., for.
Station 4089. Off Mokuhooniki Islet, Pailolo Channel, H. I. Bott.
temp. 43.8°. 297-304 fathoms. Fne. gy. s.
Station 4096. Off Mokuhooniki Islet, Pailolo Channel, H. I. Bott.
temp. 45.3°. 272-286 fathoms. Fne. gy. s.
Station 4112. Off Lae-o Ka Laau Light, Molokai, H. I. Bott. temp.
40.5°. 433-447 fathoms. Fne. s.
Station 4117. Off Kahuku Point, Oahu, H. I. Bott. temp. 45.6°.
253-282 fathoms. Co. s., for.
202 HAWAIIAN AND OTHER PACIFIC ECHINI.
Station 4130. Off Hanamaulu, Kauai, H. I. Bott. temp. 46.1°. 283-
309 fathoms. Fne. gy. s.
Station 4331. Off Hanamaulu, Kauai, H. I. Bott. temp. 43.7°. 257-
309 fathoms. Fne. gy. s.
Station 4134. Off Hanamaulu, Kauai, H. I. Bott. temp. 43.3°. 225-
324 fathoms. Fne. co. vol. s.
Station 4136. Off Hanamaulu, Kauai, H. I. Bott. temp. 44.2°. 294-
352 fathoms. Fne. co. s.
Station 4137. Off Hanamaulu, Kauai, H. I. Bott. temp. 41°. 411-
476 fathoms. Co., vol. s., for., r.
Bathymetrical range, 165-692 fathoms. Extremes of temperature, 54°-
38.2°.
"Thirty-nine specimens.
Sperosoma biseriatum Dod.
Sperosoma biseriatum Doderlein, 1901. Zool. Ariz., XXIII, p. 20. 1906. Ech. d. deut-
schen Tiefsee-Exp., Pis. XIX; XL, figs. 1-lh.
Sperosoma biseriatum Agassiz and Clark, 1907. Bull. M. C. Z., LI, p. 120.
Western Indian Ocean ; 563 fathoms.
Plate 65, figs. 15-30.
The specimen which we have referred to this species differs very markedly
from Doderlein's type, and, taking these differences in connection with the
very great geographical and bathymetrical distances between the two spe-
cimens, we have little doubt that they are not identical. But in view of
the poor condition of our specimen and the fact that in certain important
particulars it agrees well with biseriatum, it has seemed to us better to let it
remain under this name, than to attempt the diagnosis of a new species
based upon it.
The test is thicker and tougher than in Doderlein's specimen, and the
color, which is a deep violet where the epidermis is not rubbed off, is very
different. The pedicellariae also show some slight differences which we
have thought worth figuring. They are very abundant all over the test,
but only tridentate and triphyllous were found ; there seem to be no ophi-
cephalous ones. The tridentate pedicellariae (PI. 65, figs. 15, 16) have the
necks very short and the stalks 2-5 times as long as the head ; the valves
(fig. 18) are short and wide, closely in contact for practically their whole
SFEKOSOMA DURUM. 203
length, and with nearly even, scarcely at all sinuate, margins ; the middle
of the blade is filled by an extensive calcareous mesh-work ; the valves
measure from .30-1.40 mm. in length, and the width at base is about two-
thirds as much.
The triphyttoua pedicellarise (PL 65, fig. 17) are not peculiar, though neck
and stalk are both very slender; the valves (fig. 19) are very much like
those of S. obscurum, and are about .50 mm. in length.
The calcareous particles in the tube-feet (PI. 65, fig. 20) are large, per-
forated plates, half a millimeter more or less in diameter ; the largest have
rough ridges and projections near the middle. No sphoeridia were found.
The single specimen, about 175 mm. in diameter, was taken by the
" Albatross " at the following station :
Station 4766. Between Atka Island and Bowers Bank, Bering Sea;
52° 38' N., 174° 49' W. 1766 fathoms. Character and temperature of
bottom not recorded.
Sperosoma durum D6d.
Sperosoma durum Doderlein, 1905. Zool. Anz., XXVIII, p. 621. 1906. Ech. d. deutschen
Tiefsee-Exp., Pis. XVIII, figa. 2, 2a; XL, figs. 4-4n.
Western Indian Ocean ; 913 fathoms.
In addition to the characters given on p. 195, the deep purple-red color
and the presence of ophicephalous pedicellarise are interesting features of
this species, of which only a single specimen, 112 mm. in diameter, is known.
The name refers to the character of the test, which is firmer and stouter than
in biseriatum, particularly abactinally.
EXPLANATION OF THE PLATES.
Plate 60.
Plate 60.
Showing some Features of the Internal Anatomy of
Bchinothrix diadema Lovon.
1. Interior view, showing arrangement of alimentary canal ; actinal half of test and lan-
tern removed.
2. Interior view, showing part of reproductive organs, alimentary canal and perignathic
girdle; one side of test removed.
3. Alimentary canal, removed from test; natural position, seen from below.
4. Lantern and perignathic girdle in position, seen from the side, showing the rudimen-
tary Stewart's organ just below the forked end of the compass.
All figures natural size.
■ .
I
i H
0^
5
'-w
i
Plate 61.
Plate 61.
Showing some Features of the Internal Anatomy of
ASTROPYGA AND MlCROPYGA.
1, 2. Micropyga tuberculata A. Ag.
1. Interior view, showing arrangement of alimentary canal; actinal half of test and lan-
tern removed. The dotted lines surrounding unshaded parts are hypothetical, the
specimen being somewhat damaged.
2. Lantern and perignathic girdle in position, seen from the side.
3, 4. Astropyga radiata Gray.
3. Interior view, showing arrangement of alimentary canal ; actinal half of test and lan-
tern removed.
4. Lantern and perignathic girdle in position, seen from the side.
All figures natural size.
8 N
I
Plate 62.
Plate 62.
Alimentary canals of Echinothurids, removed from the tests, natural position, seen
from below.
1. Asthenosoma Ijimai Yosh.
2. Phormosoma bursarium A. Ag.
3. Echinosoma hispidum Mortens.
4. Sperosoma obscurum A. Ag. and CI.
All figures natural size.
.
'
Plate 63.
Plate 63.
Perignathic Girdles, Lanterns, and Stewart's Organs of Echinothurids, in natural posi-
tion, seen from the side.
1. Sperosoma obscurum A. Ag. and CI.
2. Asthenosoma Ijimai Yosh.
3. Phormosoma bursarium A. Ag.
4. Echinosoma hispidum Mortens.
All figures considerably enlarged.
.
63.
K-
V-*,
■
Plate 64.
Plate 64.
1-8. Arseosoma bicolor A. Ag. and CI.
1. Dactylous pedicellaria. X 70.
2. Large tridentate pedicellaria. X 30.
3. Triphyllous pedicellaria. X 70.
4. Valve of dactylous pedicellaria. X 70.
5. Valve of large tridentate pedicellaria. X 70.
6. Tip of valve of large tridentate pedicellaria. X 150.
7. Valve of small tridentate pedicellaria. X 70.
8. Valve of triphyllous pedicellaria. x 70.
9-12. Sperosoma giganteum A. Ag. and CL
9. Large tridentate pedicellaria. X 70.
10. Varve of large tridentate pedicellaria. X 70.
11. Valve of small tridentate pedicellaria. X 70.
12. Valve of triphyllous pedicellaria. X 70.
64.
Plate 65.
Plate 65.
1-3. Sperosoma giganteum A. Ag. and CI.
1. Ophicephalous pedicellaria, seen from the side. X 70.
2. The same, seen from distal end. X 70.
3. Valve of same, seen from within. X 70.
4-14. Sperosoma obscurum A. Ag. and CI.
4. Tridentate pedicellaria, with valves in contact throughout, x 30.
5. Tridentate pedicellaria, with valves in contact only at tip. x 30.
6. Valve of a tridentate pedicellaria like fig. 5. x 70.
7. Stalk of tridentate pedicellaria. X 70.
8. Stalk of triphyllous pedicellaria. X 70.
9. Ease of blade of valve of tridentate pedicellaria like fig. 4, side view, x 70.
10. Base of blade of valve of tridentate pedicellaria like fig. 5, side view, x 70.
11. Valve of a triphyllous pedicellaria. X 70.
12. Valve of another triphyllous pedicellaria. X 70.
13. Sphseridium. X 70.
14. Calcareous particles from pedicels, x 70.
15-20. Sperosoma biseriatum Dud. (1). From Station 4766
15. Large tridentate pedicellaria. x 30.
16. Small tridentate pedicellaria. X 30.
17. Triphyllous pedicellaria. X 30.
18. Valve of tridentate pedicellaria. x 70.
19. Valve of triphyllous pedicellaria. X 70.
20. Calcareous particles from pedicels, x 70.
65
11
14
13
heGB
10
i.:
//
Plate 66.
Plate 66.
1-4. Arseosoma pyrochloa A. Ag. and CI.
1. Large tridentate pedicellaria. X 30.
2. Small tridentate pedicellaria. x 30.
3. Triphyllous pedicellaria, with partly open valves, x 30.
4. Splueridium. X 30.
5. Arseosoma Belli Mortens.
5. Sphseridium. X 70.
6-17. Arseosoma thetidis A Ag. and CI.
6. Valve of very small tridentate pedicellaria. X 70.
7-10. Margins of valves of tridentate pedicellaria?. X 70.
11. Blade of valve of large tridentate pedicellaria, from within. X 70.
12. Tip of blade of large tridentate pedicellaria, side view, x 70.
13. Calcareous particles from pedicels. X 70.
14. Valve of triphyllous pedicellaria. X 70.
15. Large tridentate pedicellaria. X 30.
16. Triphyllous pedicellaria. X 30.
17. Tridentate pedicellaria. X 30.
18, 19. Arseosoma eurypatum A. Ag. and CI.
18. Sphreridia. X 70.
19. Valve of triphyllous pedicellaria. X 70.
20. Arseosoma fenestratum Mortens.
20. Dactylous pedicellaria with Jive valves, x 30.
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Plate 67.
Plate 67.
1-3. Echinosoma panamense Mortens.
1. Triphyllous pedicellaria. x 70.
2, 3. Tridentate pedicellariae. X 70.
4-11. Echinosoma hispidum Mortens.
4. Large tridentate pedicellaria. x 10.
5. Valve of large tridentate pedicellaria. X 15.
6. Ordinary small tridentate pedicellaria. X 10.
7. Valve of ordinary small tridentate pedicellaria. X 30.
8. 9. Bare forms of small tridentate pedicellariae. X 10.
10. Triphyllous pedicellaria. x 10.
11. Spheeridium. X 70.
12-15. Echinosoma tenue Pomel. From Station 3784.
12. Large tridentate pedicellaria. X 30.
13. Valve of large tridentate pedicellaria. X 30.
14. Valve of small tridentate pedicellaria. X 70.
15. Valve of triphyllous pedicellaria. X 70.
16-21. Echinosoma tenue Pomel. From Station 5084.
16. Valve of large tridentate pedicellaria. X 30.
17. Small tridentate pedicellaria. X 30.
18. Valve of small tridentate pedicellaria. X 70.
19. Triphyllous pedicellaria. X 30.
20. Valve of triphyllous pedicellaria. X 70.
21. Valve of ophicephalous pedicellaria. X 70.
.
67
Plate 68.
Plate 68.
Arasosoma thetidis A. Ag. and CI.
Abactiual view of partly denuded specimen.
Natural size.
"Albatross" Pacific and Hawaiian Echini.
Plate 68.
Heliotype Co. Boston
Plate 69.
Plate 69.
Araeosoma thetidis A. Ag. and CI.
Actinal view of same specimen as that shown on Plate 68.
Natural size.
"Albatross" Pacific and Hawaiian Echini.
Plate 69.
Heliotype Co. Boston
Plate 70.
Plate 70.
Arseosoma thetidis A. Ag. and CI.
1. Abactinal system. X 1.7.
2. Actinostome and base of corona. X 1.1.
3. Actinal ambulacral and interambulacral plates, ten millimeters from ambitus. X 1.3.
4. Abactinal ambulacral and interambulacral plates, ten millimeters from ambitus. X 1.1.
70
M
Plate 71.
Plate 71.
Araeosoma bicolor A. Ag. and CI.
1. Actinal view of partly denuded specimen.
2. Abactinal view of same.
Natural size.
Owing to an oversight of the printer the position of the figures of this plate has acci-
dentally been reversed. In all the other plates the right anterior interambulacrum is on
the right of the anterior or median ambulacrum.
"Albatross" Pacific and Hawaiian Echini
Plate 71.
Heliotype Go. Boston.
Plate 72.
Plate 72.
Arseosoma bicolor A. Ag. and CI.
1. Actinostome and base of corona, x 1.7.
2. Abactinal system. X 2.3.
3. Actinal ambulacral and interambulacral plates, seven millimeters from ambitus. X 1.8.
4. Abactinal ambulacral and interambulacral plates, eight millimeters from ambitus. X 2.
.
AMWes1-
Plate 73.
Plate 73.
Arseosoma eurypatum A. Ag. and CI.
1 . Abactinal view of nearly denuded specimen.
2. Side view of same, looking towards an interambulacrum.
Natural size.
"Albatross" Pacific and Hawaiian Echini.
Platk 73.
Heliotype Go. Boston
Plate 74.
Plate 74.
Arseosoma eurypatum A. Ag. and CI.
Actinal view of same specimen as that shown on Plate 73.
Natural size.
"Albatross" Pacific and Hawaiian Echini.
Heliotype Co. Boston.
Plate 75.
Plate 75.
Araeosoma eurypatum A. Ag. and CI.
1. Actinostome and base of corona, somewhat damaged, x 1.3.
2. Abaetinal system. X 2.
3. Actinal ambulacral and interambulacral plates, five millimeters from ambitus, x 1.5.
4. Abaetinal ambulacral and interambulacral plates, just above ambitus, x 1.3.
75
:
Plate 76.
Plate 76.
AraBosoma leptaleum A. Ag. and CI.
1. Abactinal view of partly denuded specimen.
2. Actinal view of same.
Natural size.
"Albatross" Pacific and Hawaiian Echini
Plate 76.
Heliotype Co Boston.
Plate 77.
Plate 77.
Araeosoma leptaleum A. Ag. and CI.
1. Actinostome and base of corona. X 1.8.
2. Abactinal system, x 2.
3. Actinal ambulacral and interambulacral plates twelve millimeters from ambitus. X 1.6-
4. Abactinal ambulacral and interambulacral plates eight millimeters from ambitus. X 2.
77
Plate 78.
Plate 78.
Arseosoma pyrochloa A. Ag. and CI.
Abactinal view of partly denuded specimen.
Natural size.
"Albatross" Pacific and Hawaiian Echini
Plate 78.
Heliotype Co. Boston.
Plate 79.
Plate 79.
AraBosoma pyrochloa A. Ag. and CI.
Actinal view of same specimen as that shown on Plate 78.
Natural size.
"Albatross" Pacific and Hawaiian Echini.
Plate 79.
Heliotype Co. Boston
Plate 80.
Plate 80.
Areeosoma pyrochloa A. Ag. and CI.
1. Actinostome and base of corona, x 1.3.
2. Abactinal system, x 2.
3. Actinal arabulacral and interanibulacral plates, nine millimeters from ambitus.
Slightly reduced.
4. Abactinal ambulacral and interambulacral plates, nine millimeters from ambitus.
Natural size.
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Plate 81.
Plate 81.
1, 2, 6, 6. Araeosoma Owstoni Mortens, juv.
1. Abactinal view of partly denuded specimen.
2. Aetinal view of same.
5. Abactinal view of partly denuded very young individual.
6. Actiual view of same.
3, 4. Arseosoma gracile A. Ag. and CI., q juv.
3. Abactinal view of partly denuded specimen.
4. Aetinal view of same.
All figures natural size.
"Albatross" Pacific and Hawaiian Echini.
Plate 81
■A4i-
Heliotype Go. Boston.
Plate 82.
Plate 82.
1-4. Araeosoma Owstoni Mortens., juv.
1. Actinostome and base of corona of young individual shown in figures 5 and 6,
Plate 81. X 5.
2. Abactinal system of same, x 5.
3. Actinal ambulacral and interambulacral plates, just below ambitus, x 5.
4. Abactinal ambulacral and interambulacral plates, just above ambitus. X 5.
6-8. Araeosoma gracile A. Ag. and CI., ? juv.
5. Actinostome and base of corona of individual shown in figures 3 and 4, Plate 81. X 4.
6. Abactinal system of same. X 5.
7. Actinal ambulacral and interambulacral plates, just below ambitus. X 4.
8. Abactinal ambulacral and interambulacral plates, just above ambitus, x 5.
[I
82
Plate 83.
Plate 83.
Speroeoma giganteum A. Ag. and CI.
Abactinal view of partly denuded specimen.
About two-thirds natural size.
"Albatross" Pacific and Hawaiian Echini.
Plate 83.
•-was ~^\ I
HehoLype Go. Boston
Plate 84.
Plate 84.
Sperosoma giganteum A. Ag. and CI.
Actinal view of same specimen as that shown on Plate 83.
About two-thirds natural size.
"Albatross" Pacific and Hawaiian Echini.
84
Heliotype Co. Boston.
Plate 85.
Plate 85.
Sperosoma giganteum A. Ag. and CI.
1. Abactinal system, x 1.5.
2. Actinostome and base of corona. Natural size.
ft
85
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Plate 86.
Plate 86.
Sperosoma giganteum A. Ag. and CI.
1. Actinal ambulacral and interambulacral plates, three millimeters below ambitus.
Natural size.
2. Abactinal ambulacral and interambulacral plates, ten millimeters above ambitus.
Natural size.
-
86
A M.Vesterjren del
th Boston
Plate 87.
Plate 87.
Sperosoma obscurum A. Ag. and CI.
Abactinal view of partly denuded specimen.
Natural size.
"Albatross" Pacific and Hawaiian Echini.
e87.
^PC*u
Heliotype Co. Boston.
Plate 88.
Plate 88.
Sperosoma obscurum A. Ag. and CI.
Actinal view of same specimen as that shown on Plate 87.
Natural size.
"Albatross" Pacific and Hawaiian Ec
Plate 88.
Heliotype Co. Boston
Plate 89.
Plate 89.
Sperosoma obscurum A. Ag. and CL.
1. Actinostome and base of corona, x 2.
2. Abactinal system, x 2.
3. Actinal ambulacral and interambulacral plates, just below ambitus, x 1.3.
4. Abactinal ambulacral and interambulacral plates, just above ambitus, x 1.2.
"Albatr
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